The Motivational Dynamics of Retrieval-Induced Forgetting

Abstract

Two experiments addressed the phenomenon of retrieval-induced forgetting (RIF) from the standpoint of cognitive energetics theory (CET). Consistent with the inhibitory account of RIF and with the notion that inhibition can be demanding and resource dependent, we found that where the inhibitory activity was difficult (vs. easy), defining a high restraining force according to the CET, RIF occurred only in the presence of a high driving force combining an elevated motivation to inhibit with the availability of high resources. Overall, the current work highlights the crucial role of motivation in producing the RIF and the way in which this phenomenon abides by the general principles of motivated cognition.

Keywords

retrieval-induced forgetting motivation need for cognitive closure cognitive resources inhibition

The present work brings into common focus three lines of theory and research in social/cognitive psychology to explore the retrieval process in reconstructive memory. These streams of work concern the studies of (a) retrieval-induced forgetting (RIF), (b) cognitive energetics, and (c) need for cognitive closure (NfCC). The retrieval process, typically treated as a purely cognitive phenomenon is assumed here to result from a driving force arising from a combination of cognitive resources and epistemic motivation (NfCC); this highlights the sense in which retrieval of items from memory essentially constitutes a judgment (about the way things were), affected by motivational factors that influence all judgments.

Cognitive Energetics Theory (CET)

According to the CET (Kruglanski et al., 2012) the execution of cognitive activity is energy-dependent. It requires that the energy allotment to a given activity (referred to as the potential driving force behind the activity) be equal or greater than the energetic demands the activity poses (i.e., the restraining force opposing the activity). The magnitude of the potential driving force is determined by a conjunction of two factors: the magnitude of motivation to carry out the activity and the pool of cognitive resources available to the individual at the time. Motivational magnitude is assumed to determine the proportion of available cognitive resources recruitable in service of the activity. In and of itself, availability of resources does not determine the amount of energy an individual is prepared to invest in an activity. The additional factor is the magnitude of motivation to carry out the activity: Given the same amount of resources, the portion that an individual would be prepared to spend on an activity, that is, the potential driving force, is determined by her or his motivation.

The potential driving force is distinct from the amount of resources that are actually recruited, which comprises the effective driving force.¹ The latter is suited to the activity’s requirements, reflecting the magnitude of the restraining force determined by difficulty (task demands) presented by the activity (as well as by the presence of competing objectives and individual’s degree of cognitive conservatism, both of little relevance to the present research).

We are assuming that just like other cognitive activities related to judgment, retrieval of items from memory is energy-dependent and its occurrence is contingent on the relative magnitudes of the potential driving force versus the restraining force present at the moment. As already noted, the potential driving force is determined by the pool of available cognitive resources and the magnitude of motivation to carry out the experimental task: the strength of the desire to confidently retrieve the required items. We assumed that the NfCC (Kruglanski, 2004; Kruglanski, Pierro, Mannetti, & De Grada, 2006; Kruglanski & Webster, 1996) represents such a motivation.

NfCC

The need for cognitive closure (NfCC) was defined as a “desire for a firm answer to a question, any firm answer as compared with confusion and/or ambiguity” (Kruglanski, 2004, p. 6). There is evidence that the need for closure can be induced by situational factors, for example, by time pressure, noise, or fatigue (Kruglanski & Freund, 1983; Kruglanski, Webster, & Klem, 1993; Webster, Richter, & Kruglanski, 1996) and that it also represents a dimension of individual differences (Webster & Kruglanski, 1994). It is a motivation to make assured judgments and to protect them from interference. Under a heightened need for closure, individuals tend to become impervious to subsequent information that could potentially undermine their prior judgments and impressions. As shown subsequently, there is a substantial body of evidence that retrieval of items from memory requires a focus on the class of items to be recalled and imperviousness to other items that could run interference with the retrieval process. Accordingly, it seems plausible that a heightened need for closure would augment such imperviousness. The process whereby the latter may be carried out has been investigated in the memory domain within a paradigm known as RIF. We now proceed to describe the latter paradigm in some detail.

RIF

The phenomenon of forgetting has long captured the interest of cognitive psychologists (e.g., J. R. Anderson, 1983; Lehman & Malmberg, 2009; Wixted, 2004). Although forgetting is often treated as a memory defect, and people typically deplore their forgetfulness, forgetting serves a fundamentally adaptive function. Forgetting some information may afford remembering other, more useful, information and avoiding unmanageable cognitive confusion.

A traditional account of forgetting has been in terms of interference (J. R. Anderson, 1983; Mensink & Raaijmakers, 1988; Wixted, 2004). On this view, multiple memories can be associated with the same cue, and a memory that is accessible at one point in time may become inaccessible (or forgotten) at another moment. This occurs when that memory’s accessibility is crowded out by interference from another memory, more strongly associated with the common retrieval cue.

Classic associative theories of interference portrayed forgetting as a passive consequence of “crowding out” of a given memory by another. However, human capacity for inhibition and suppression (Forster, Liberman, & Higgins, 2005; Kunda & Spencer, 2003; Shah, Friedman, & Kruglanski, 2002) suggests that forgetting need not be passive, but rather may be driven by an active striving to advance one’s current goals: Inhibiting information that is unnecessary, inappropriate, and irrelevant to one’s current concerns may serve to remember information that is necessary, appropriate, and relevant (Storm, 2011).

A form of such thought control has been investigated in research on RIF initiated by Anderson et al. (M. C. Anderson, Bjork, & Bjork, 1994). In a unique experimental paradigm (described subsequently), these authors have shown that retrieval of a given memory can cause the forgetting of other related memories. Moreover, it has been argued that forgetting can be seen as a consequence of an inhibitory-control process that enables the overcoming of interference during retrieval. On this view, one’s ability to retrieve a desired item from memory is made possible through inhibition, and thus “forgetting” of other unwanted items.

The Retrieval-Practice Paradigm

RIF has been investigated within the Retrieval-Practice Paradigm (M. C. Anderson et al., 1994). In an experimental situation, research participants first study a list of (e.g., COLOR-Black; FRUIT-Apple; ANIMAL-Elephant) and then recall half of the exemplars (Rp+ items) of half of the categories. The recall task is facilitated by a two letter-stem-cue (e.g., COLOR-Bl___) to ensure that participants retrieve the exact required items. After completing a distractor task (i.e., anagrams), participants move on to a final memory test on all the studied exemplars of all the categories.

This procedure affords an assessment of recall performance on three item types: Rp+ items (the retrieval-practiced items from practiced categories; e.g., COLOR-black); Rp– items (the retrieval-non-practiced items from practiced categories; e.g., COLOR-brown); and Nrp items (the non retrieval-practiced items from nonpracticed categories; e.g., ANIMAL-elephant). Facilitation value of Rp+ items is calculated as the difference between Rp+ items and Nrp (control) items; whereas RIF value is calculated as the difference between Nrp items and Rp– items.

As already noted, an account for the RIF effect has been in terms of an inhibitory process. In other words, the memory impairment of the nonpracticed (Rp–) items was assumed to reflect an inhibition of competing items designed to prevent their entry into conscious awareness.

On this view (M. C. Anderson, 2003), competition among items is a necessary condition for RIF, because if an item does not compete for access, it does not need to be inhibited. In this vein, M. C. Anderson et al. (1994) manipulated category composition (selecting items of high vs. low taxonomic frequency) to vary item-competition. Consistent with the idea that only interfering items are inhibited, the authors found that retrieval practice produced more RIF effect in high frequency competitors (e.g., Fruit-Orange) than in low frequency competitors (e.g., Fruit-Kiwi).

Inhibition is often conceptualized as a demanding, resource-intensive process (Muraven & Baumeister, 2000; Ortega, Gomez-Ariza, Romàn, & Bajo, 2012). If inhibition constitutes a mechanism of RIF, resource restriction should accordingly attenuate RIF (defining the executive deficit hypothesis; M. C. Anderson & Levy, 2008). This prediction was corroborated in research that found a decrement in successful suppression of irrelevant responses as a function of working memory load (Engle, Conway, Tuholski, & Shisler, 1995) and studies that have considered the role of cognitive load in RIF. In particular, research by Romàn, Soriano, Gòmez-Ariza, and Bajo (2009) found that RIF effect is diminished when participants engage in a secondary task (which overloads attentional resources and thus impedes the ability to inhibit unwanted items) during the retrieval-practice phase. Similarly, Koessler, Engler, Riether, and Kissler (2009) have found that the RIF effect disappears when stress is induced in nonclinical participants. Furthermore, Aslan and Bäuml (2010) provided evidence for a positive relationship between working memory capacity (WMC) and RIF whereby high-WMC individuals display a more pronounced RIF than low-WMC individuals. These results provide mounting evidence for the inhibitory executive control account of RIF and corroborate the close link between WMC (as measured by OSPAN) and inhibitory efficiency. Interestingly in this connection, Groome and Grant (2005) found a significant negative correlation between RIF and Cognitive Failure Questionnaire (CFQ) scores, indicating that individuals who tend to display stronger RIF effects tend to suffer a lower rate of cognitive failures and overall forgetfulness in everyday life, both presumably affected by the presence of cognitive resources.

Research reviewed above is consistent with the view that RIF is governed by demanding inhibitory processes (Levy & Anderson, 2008; Macrae & MacLeod, 1999) whose performance requires cognitive resources. However, several questions remain. One question concerns the nature of the cognitive resources that play a role in RIF and the range of factors that affect its availability. As a working hypothesis, we assume that the pool of resources constitutes a finite quantity (e.g., assessed as a WMC) depletable by prior or concurrent cognitive activity (e.g., concurrent cognitive load) and also by individuals’ general states of fatigue versus vitality.

A different question is whether the mere presence of resources suffices to produce the RIF effect. Presumably, resources do not have a mind of their own and are necessarily geared toward satisfying a given motivation, or progressing to a given goal. Yet the role of motivation in RIF has not been explored so far.² It seems plausible to assume that in the absence of a sufficiently strong motivation to recall given items, resources wouldn’t matter much; hence, that little or no RIF would occur in those circumstances.

The Present Research

Following the above considerations, we assumed that when people are highly motivated to inhibit irrelevant memories and have sufficient cognitive resources to sustain their motivation, irrelevant thoughts should be inhibited and therefore forgotten. As suggested by the CET, where the inhibition of irrelevant memories is difficult to accomplish,³ that is, in presence of a considerable “restraining force,” proportionately ample extent of motivation and resources, defining a high magnitude of the potential driving force (which delimits the possible effective driving force) is required to control the interference from goal-irrelevant items. In contrast, where the inhibition of irrelevant memories is easy to achieve, defining a restraining force of a low magnitude, attaining the inhibitory goal should require lesser magnitudes of motivation and resources, that is, a potential driving force of a lower magnitude.

We assumed that in the context of a recall task, the NfCC represents a motivation to have confidence in one’s recalled items. To that end, individuals with a high (vs. low) NfCC may have a strong motivation to assuredly recall the items on the list and protect selective retrieval from interference of irrelevant items. We also assumed that the amount retrieval practice would define the difficulty of the task. Where the amount of retrieval practice is low, the act of managing the interference of competing memories would require a relatively considerable degree of NfCC and cognitive resources and would manifest itself in a high RIF. In contrast, if the amount of retrieval practice is high, the act of managing the interference would be relatively easy. In these circumstances, one should expect an easier forgetting of competing items (Rp– items). Therefore, greater RIF is expected where selective retrieval is repeated several times because of the low difficulty in managing the interference from competing items. In contrast, a lesser RIF is expected where selective retrieval is low because of the stronger difficulty in overcoming the interference of Rp– items, therefore, substantial RIF should require a joint presence of both high NfCC and resources.

To test these predictions we conducted two studies. In Study 1, we investigated the role of motivation and cognitive resources on the RIF effect in the standard retrieval-practice paradigm. In this research, we examined how participants’ NfCC influences the extent to which they tend to suppress unwanted thoughts as a function of cognitive resource availability (i.e., testing participants at times of circadian matches vs. circadian mismatches). The RIF effect was examined with only two retrieval-practice repetitions across the board, and we manipulated the taxonomic frequency (i.e., category prototypicality) of the Rp– items as a control measure for inhibition underlying the RIF effect. We assumed that where the Rp– are prototypical, their accessibility is high and they exert high interference, so that to overcome it, one would need a high combination of motivation (NfCC) and resources. Where the Rp– items are low on prototypicality, however, the interference they would pose is low; hence, no or little inhibition would be required. In this condition, the recall task would seem to be rather easy, requiring no inhibition of the Rp– items and thereby producing little RIF.

The aim of Study 2 was to conceptually replicate Study 1 with a different memory task and a different operationalization of cognitive resources (i.e., via the OSPAN task). Furthermore, whereas in Study 1, we kept the accessibility of the Rp+ items constant (via two retrieval-practice repetitions across the board) and varied the strength (category prototypicality) of the Rp– items, in Study 2 we included only strong (i.e., high prototypicality) Rp– items and varied the strength (accessibility) of the Rp+ items by manipulating the number of retrieval-practice repetitions (two vs. four). In line with the CET, we assumed that when the inhibitory task is easy (i.e., comprising four retrieval-practice repetitions) as opposed to difficult (comprising two retrieval-practice repetitions) high resources/motivation should be less necessary to produce recall. A detailed description of our studies is given below.

Study 1

The aim of Study 1 was to test the (motivational) role of the NfCC as it interacts with cognitive resources to produce the RIF. We used the classic retrieval-practice paradigm and gave all our participants a low degree of practice, namely, two practice trials (i.e., below the standard practice of three trials, common in RIF research). To manipulate cognitive resources, some individuals were tested at their circadian match (i.e., morning types tested in the morning and evening types tested in the evening) and others at their circadian mismatch (i.e., morning types tested in the evening and evening types tested in the morning).

Previous research has shown that that the amount of inhibition depends on the amount of retrieval practice that people experience (Johnson & Anderson, 2004; Levy et al., 2007; Storm, et al., 2008). Therefore, we expected that in the present case where the amount of retrieval practice was low, the amount of energy needed to reach the inhibitory goal would be high. In other words, we hypothesized that the “driving force” (determined by a conjunction of the NfCC and cognitive resources) should be sufficiently high to overcome the “restraining force” (produced by the high inhibition difficulty under low retrieval practice).

Furthermore, as shown by M. C. Anderson et al. (1994), high (vs. low) taxonomic frequency items interfere more with recall of the practiced items; hence, they are in a greater need of inhibition to accomplish the retrieval of the practiced items. Therefore, we also manipulated category composition, thereby forming four categories with items with high taxonomic frequency (high accessibility, e.g., “mass media-television”) and four categories with items with low taxonomic frequency (low accessibility; e.g., “fruit-mango”). This manipulation served as a control measure for inhibition underlying the RIF effect. We expected our hypotheses to be supported for high taxonomic frequency items (that presumably require inhibition) and not for low taxonomic frequency ones (that presumably do not).

Method

Participants and design

One hundred and two native Italian-speaking psychology students (64 females, 38 males, M_age = 26.21, SD_age = 7.72) from the University of Rome “La Sapienza” participated in the study for extra course credit. Following the procedure of Kruglanski and Pierro (2008), the experiment proceeded in two phases. During the first phase, participants completed the short NfCC scale (Revised NfCS) and the morningness scale described below. In the second phase, approximately 1 week later, participants performed the retrieval-practice task following the procedure recommended by M. C. Anderson and colleagues (1994). In this phase, participants were randomly assigned to the circadian match versus circadian mismatch conditions. Following M. C. Anderson and colleagues, category composition (strong vs. weak taxonomic frequency of items) and Item Types (Rp+; Rp–; Nrp) were manipulated within participants.

Procedure

We used M. C. Anderson et al’s. (1994) retrieval-practice paradigm. Subjects were told that they were participating in an experiment on learning and memory. As in Kruglanski and Pierro’s (2008) procedure, subjects were previously categorized as morning types or evening types based on a median split of the morningness scale’s scores. Specifically, participants completed the retrieval-practice task in either one of two different time sessions to manipulate their match or mismatch with their morningness score, namely during (a) morning sessions (7-8 a.m.) and (b) evening sessions (7-8 p.m.). The matching variable was manipulated between subjects. In the match condition, “morning type” participants performed the experiment in the morning, and “evening type” participants did so in the evening. In the mismatch condition, “morning” subjects performed the task in the evening and “evening” subjects in the morning.

The retrieval-practice task consisted of four phases: (a) study; (b) retrieval practice; (c) distractor, and (d) final memory test. In the study phase, subjects memorized 60 category-exemplar word pairs (e.g., “metal–steel”), which were displayed for 5 s on the center of the screen, so they could remember each exemplar with its respective category. Similar to M. C. Anderson and colleagues (1994), we used four categories entirely composed of strong exemplars (e.g., “Fruit-Apple”) and four categories entirely composed of weak exemplars (e.g., “Fruit-Mango”). Two filler categories (one strong and one weak), with six exemplars each, were displayed at the beginning and end of each trial to control for primacy and recency effects on memory. Two items from the same category were never presented consecutively and items presentation order was counterbalanced.

In the retrieval-practice phase, participants were told that they would see some category words and two letters stem cues on each trial (e.g., “Metal-St___”). We displayed in this manner half of the exemplars (i.e., three items) from half of the categories (i.e., four categories), plus the two filler categories (i.e., two control categories) at the beginning and end of each trial. Participants were instructed to retrieve and write down the exact example that was associated with the category word, which began with the letters stem cues that were shown. Participants practiced the retrieval-practice phase twice for 10 s for each category-exemplar pair for each trial. The same category-exemplar pair was never presented consecutively and items presentation order was counterbalanced.

Subsequently, subjects completed anagrams as a distractor task for 15 min before moving on to the final phase. In the final phase, participants were asked to remember and write down all the exemplars for each category encountered during the entire study. Precisely, each category word appeared on top of the screen for 30 s, during which participants were asked to write the requisite exemplar words. As in the previous phases of the paradigm, the presentation order was counterbalanced. At the end of the experiment, participants were thanked and debriefed. None evidenced any awareness of the hypotheses.

Materials

Morningness scale

The degree to which a participant was a morning or an evening type was assessed using an instrument developed by Smith et al. (1989). It is a 13-item composite scale that integrates the best items from two commonly known morningness scales developed by Horne and Ostberg (1976) and by Torsvall and Akerstedt (1980). A sample item of this scale is, “one hears about morning and evening types of people. Which one of these types do you consider yourself to be?” (1 = Definitely an evening type; 2 = More an evening than a morning type; 3 = More a morning than evening type; 4 = Definitely a morning type). A composite morningness score was computed by summing up the participants’ responses to each item. Reliability of the morningness scale was satisfactory (α = .81). As mentioned before, participants were categorized as morning types or evening types on the basis of a median split (Me = 35) of the morningness score. Scores ranged from 18 (extreme evening type) to 50 (extreme morning type). The general mean on the morningness scale was 34.73 (SD = 5.52). The mean score on the morningness scale for “morning type” participants was 31.20 (SD = 3.55), whereas for “evening type” participants it was 39.56 (SD = 3.81). The difference between the two groups was significant, F(1, 100) = 129.55, p < .001, η_p² = .56. This result suggests that even though young adult students are typically more evening than morning oriented (Lieberman, Wurtman, & Teicher, 1989), in the present sample, there was a sufficient variability to divide them into two separate and distinct groups of “morning type” participants versus “evening type” participants as required by our research design.

NfCC

To assess the NfCC, participants responded to the Italian version of the Revised NfCS (Pierro & Kruglanski, 2005). The Revised NfCS is a 14-item self-report scale that measures stable individual differences in the NfCC. It requires respondents to rate the extent to which they agree with each statements (e.g., “any solution to a problem is better than remaining in a state of uncertainty”). Participants’ responses are recorded on a 6-point scale ranging from 1 (strongly disagree) to 6 (strongly agree). A composite need for closure score was computed by summing up responses to each item. The reliability (Cronbach’s alpha) of the Revised NfCS scale was satisfactory (α = .80).

Retrieval-practice task

All stimuli were chosen from Italian norms for category production (Boccardi & Cappa, 1997). Following M. C. Anderson et al. (1994), we selected ten relatively nonassociated and dissimilar categories to ensure that they would not interfere with one another. Each category comprised six unambiguous and noncompound exemplars in which no two exemplars began with the same first two letters to avoid interference during the retrieval-practice phase. Category composition (strong vs. weak) was manipulated to test the inhibitory process underlying the RIF effect. Strong categories contained exemplars with high taxonomic frequency; and weak categories contained exemplars with low taxonomic frequency.

Manipulation check

After the retrieval-practice task, participants responded to the following two items to assess their perceived cognitive capacity at the time they were tested: “At this time it is difficult for me to carefully consider my answers to these questions,” and “at this time I feel mentally fatigued.” Responses to these questions were recorded on a 7-point scale ranging from 1 (extremely false) to 7 (extremely true). These responses were highly inter-correlated, so we computed a composite score for perceived cognitive capacity by averaging across the two responses (α = .90).

Results

Manipulation check

Results of a one-way analysis of variance (ANOVA) performed on participants’ perceived cognitive capacity ratings yielded a significant effect of circadian matching, F(1, 100) = 16.25, p < .001, η_p² = .14, with lower perceived resource capacity in the mismatch condition (M = 3.83, SD = 1.21) than in the match condition (M = 2.73, SD = 1.23). This result indicates that our manipulation was successful in capturing a depletion of participants’ cognitive resources.

Retrieval practice

Retrieval rates for Rp+ items varied as a function of category composition: These rates were 75% (SD = 17.19) for the weak and 90.69% (SD = 12.54) for the strong Rp+ items and were statistically different from one another, F(1, 101) = 70.39, p < .001, η_p² = .41. This finding is consistent with previous data that high taxonomic items tend to be recalled more easily than low taxonomic ones (M. C. Anderson et al., 1994) and confirms our manipulation of category composition of strong versus weak.

Multiple regression analyses were conducted to assess the influence of circadian matching conditions (contrast coded: Mismatch = -1; Match = 1), NfCC, and their interaction on retrieval rates for each category composition (strong and weak categories). In the strong categories, no main effects were found for circadian matching (β = −.19, t = −1.91, p > .05) and NfCC (β = .06, t = .56, p > .5) or for their interaction (β = .01, t = .10, p > .9). Similar nonsignificant effects were found in the weak categories, (circadian matching, β = −.03, t = −.25, p = .8; NfCC, β = −.15, t = −1.43, p > .1; interaction effect, β = .11, t = 1.08, p > .2). These results suggest that, as expected, there was no effect of circadian matching, NfCC, and their interaction on retrieval rates for strong and weak items.

Facilitation effect

To determine whether the retrieval practice produced the expected facilitation effect, we conducted 2 one-way ANOVAs (one for strong categories, the other for weak categories) with item type (Rp+ and Nrp) as a repeated measures factor. These analyses revealed a significant main effect of item type on retrieval rates for strong (Rp+ = 74.02%, SD = 21.31; and Nrp = 41.91%, SD = 14.85; F(1, 101) = 189.56, p < .001, η_p² = .65) and weak items (Rp+ = 58.17%, SD = 22.83; and Nrp = 29.66%, SD = 13.95; F(1, 101) = 146.21, p < .001,η_p² = .59). Therefore, as expected, retrieval practice produced the facilitation effect for strong and weak items. We computed the facilitation effect for strong and weak categories by subtracting the recall percentage of Nrp items from the recall percentage of Rp+ items [facilitation effect = (Rp+) − (Nrp)].

To examine the effect of circadian matching, NfCCs and the interaction between them on the facilitation effect, two multiple regression analyses were performed, one per each category composition (i.e., strong and weak categories). In the strong category condition, no main effects were found for circadian matching (β = .06, t = .60, p > .5) and NfCC, β = −.11, t = −1.04, p > .3), nor for their interaction (β = −.05, t = −.51, p > .6). Similar nonsignificant effects were found in the weak categories (circadian matching, β = −.10, t = −.95, p > .3; NfCC, β = .01, t = .06, p > .9; interaction effect, β = −.05, t = −.52, p > .6). As expected, these results suggest that there was no effect of circadian matching, NfCC, and their interaction on the facilitation effect for either strong or weak items.

RIF

To determine whether the retrieval practice produced the expected RIF effect, we conducted 2 one-way ANOVAs (one for strong categories, the other for weak categories) on recall rates with item type (Nrp and Rp−) as a repeated measures factor. Results for weak category condition (weak Nrp = 29.66%, SD = 13.95; weak Rp− = 26.96%, SD = 19.91) revealed no significant RIF effect, F(1, 101) = 1.98, p > .1, η_p² = .02. In this condition, items did not compete for access into conscious awareness; hence, as expected, no RIF was found.

On the other hand, results for strong categories (strong Nrp = 41.91%, SD = 14.85; strong Rp− = 30.07%, SD = 19.63) indicated a significant main effect of item type, F(1, 101) = 29.12, p < .001, η_p² = .22. As expected, retrieval practice produced the RIF effect for items in the strong categories but not for items in the weak categories, thereby suggesting that a necessary condition for RIF is the interference of competing items: The more a given word interferes with the recall of a desired item the more it becomes inhibited, difficult to retrieve, and thus forgotten.

In light of these findings, we computed the RIF effect only for the strong categories by subtracting the recall percentage of Rp− items from the recall percentage of Nrp items [RIF effect = (Nrp) − (Rp−)]. Our prediction regarding the effect on RIF of the interaction between NfCC and circadian matching (contrast coded: Mismatch = −1; Match = 1) was tested by means of the moderated multiple regression analysis (using the product variable approach suggested by Baron and Kenny (1986). In this analysis, we entered the main effects of NfCC, circadian matching, and their interaction. Following Aiken and West (1991), NfCC score was centered (i.e., by subtracting the mean from each score), and the interaction term was based on these centered scores. This analysis revealed no significant main effects of circadian matching (β = .07, t = .68, p > .5) or of NfCC (β = .04, t = .35, p > .7). More importantly, the interaction between NfCC and circadian matching was significant, β = .21, t = 2.11, p < .05, suggesting that, as predicted, the RIF effect was maximized for high need for closure participants in the circadian match (vs. mismatch) condition. This finding was illustrated via the predicted mean values showed in Figure 1. Following the suggestion of Aiken and West, these were values one standard deviation above and one standard deviation below the means of the relevant variables in the pertinent regression equations. To further probe the nature of this interaction effect, we performed simple slope analyses, in accordance with Aiken and West’s recommendation. These analyses revealed that the relationship between NfCC and RIF was significant and positive for participants in the match condition, β = .26, t = 2.03, p < .05, whereas this relationship was nonsignificant for participants in the mismatch condition, β = −.18, t = −1.11, p > .2.

Figure 1.

Retrieval-induced forgetting as a function of Circadian match and need for cognitive closure (Study 1).

In addition, to check whether the effects of circadian matching were similar for morning and evening participants, two multiple regression analyses were performed separately for these two types of persons. The results confirmed that the 2-way interaction between NfCC and circadian matching was similar for morning types, β = .20, t = 1.41, p = .16, and evening types, β = .28, t = 1.82, p = .08.

Discussion

Results of our Study 1 confirmed the inhibitory nature of RIF effect and, furthermore, lent support to our model. As inhibition is concerned, we replicated M. C. Anderson et al.’s (1994) finding that the RIF effect was obtained only for strong category words, that is, where the Rp− items offered a considerable competition to the cued Rp+ items, but not for weak category words where competition from the Rp− items was slight.

As our predictions are concerned, we had assumed that with two practice trials only, where strengthening the accessibility of the Rp+ items was relatively mild, competition from the Rp− items would be relatively intense, making the inhibition task difficult and augmenting the magnitude of the restraining force. We had predicted that in this situation a strong driving force would be necessary to protect retrieval of the practiced items. This expectation was confirmed by the 2-way interaction between availability of cognitive resources (i.e., circadian match) and the motivation toward closure. In other words, only where resources were ample and the motivation to draw on them was strong did the inhibitory effect occur.

Although the results of Study 1 are encouraging, a number of questions remain: First, we assumed that the RIF effect in this study would require a combination of high motivation and ample resources because the inhibition task with two only practice trials is difficult to accomplish, creating a strong restraining force. To compellingly demonstrate that this is the case, one would need a comparison condition where the restraining force is weak, in which case RIF should be obtained under a relatively low driving force (defined by lower motivation and/or resources). Second, the operationalization of resources in terms of circadian rhythm, though interesting, is rather unique. Potentially, the circadian match and mismatch conditions differed from each other in ways other than in resource availability. Possibly, people’s affective states in the match condition could be more positive than in the mismatch condition and this could account, perhaps, for our results. Finally, it seems likely that the categories used in Study 1 had no particular significance to our research participants. Hence, we deemed it appropriate to investigate our theory in a context of greater real-world relevance. Study 2 was, therefore, carried out to address the limitations of its predecessor.

Study 2

Study 2 constituted an extended replication of Study 1 in which we varied inhibition difficulty at two levels, employed a different operationalization of cognitive resources, and used brand names as items in the memory task. To manipulate the difficulty of inhibition, we varied the amount of retrieval practice (two vs. four retrieval-practice repetitions). Furthermore, we assessed cognitive resources differently from Study 1, namely, by assessing our participants’ WMC (OSPAN). The NfCC was measured via the appropriate scale as in Study 1. We reasoned that where the amount of retrieval practice is high (four retrieval-practice repetitions), the inhibitory task is relatively easy to accomplish; therefore, the amount of energy needed to reach the inhibitory goal should be low. In this condition, individuals should be able to inhibit and hence, forget, unwanted items relatively independent of their WMC (OSPAN score) and NfCC. As in Study 1, however, we expected that where the amount of retrieval practice is low (i.e., two retrieval-practice repetitions), inhibition should be relatively difficult to accomplish, so the amount of energy needed to produce it should be relatively high. According to this rationale, a conjunction of high need for closure and high WMC should combine to produce stronger inhibition, thereby resulting in a more pronounced RIF than where the magnitudes of either or both these variables are low.

Method

Participants and design

Ninety-four native Italian-speaking psychology students (60 females, 34 males, M_age = 23.50, SD_age = 3.49) from the University of Rome “La Sapienza” participated in the study for extra credits. The number of repetitions (2 vs. 4) during the retrieval-practice phase of the Retrieval-Practice Paradigm was manipulated between subjects: One group performed retrieval-practice phase two times (two retrieval-practice repetitions), whereas the other performed it four times (four retrieval-practice repetitions). Last, we measured the OSPAN score and NfCC. As in Study 1, the dependent variable was the degree of impairment in recall of the Rp− items relative to the Nrp items in the Retrieval-Practice Paradigm.

Procedure

Subjects were told that they are participating in two experiments. The first was a study of brand memory and the second, a pretest of a new memory task (i.e., OSPAN task). No participant reported that the two tasks were associated. Participants first performed the Retrieval-Practice Paradigm (M. C. Anderson et al., 1994) adapted to product categories and brand names as exemplars of each category. Last, they performed the OSPAN task and filled out a questionnaire that included the NfCC scale. As in Study 1, the Retrieval-Practice Paradigm consisted of four phases: (a) study; (b) retrieval practice; (c) distractor phase and (d) final memory test. In the study phase, subjects memorized 60 category-brand word pairs (consisting of eight different brand categories, plus two filler brand categories; e.g., “Car-Peugeot”), which were displayed for 5s. The words were centered on the screen, so that participants could remember each brand linked with its category. Two filler categories, with six brands each, were displayed in the first and last positions of each trial to control for primacy and recency effects. Two brands from the same category were never presented consecutively and the presentation order of the items was counterbalanced. In the retrieval-practice phase, participants were additionally instructed that they would see some category words and two letters stem cues on each trial (e.g., “Car-Pe___”). In this manner, we displayed half of the brands (i.e., three brands) from half of the categories (four categories) plus the two filler categories at the beginning and end of each trial. Participants’ task was to retrieve and type in the exact brand name that was associated with the category word and began with the letters appearing with the stem cue. The time per each category-brand pair in this phase was about 10s. The same category-brand pair was never presented consecutively and the presentation order was counterbalanced.

Participants performed anagrams as a distractor task for 15 min before moving on to the final test phase. At that time, they were asked to remember and write down all the brands for each category they encountered during the entire study. Each category word appeared on top of the screen for precisely 30s and participants wrote down the appropriate brand names at the bottom of the screen. As in the previous phases of this procedure, the presentation order was counterbalanced. Once this activity was completed, participants were thanked and debriefed. None of the participants evinced any awareness of the hypotheses.

Materials

Retrieval-practice task

Following M. C. Anderson et al. (1994), we selected 10 different and relatively nonassociated categories (i.e., Moto, Toothpaste, Beer, Cigarette, Jeans, Pasta, Water, Coffee, Car, Shampoo) to ensure that they would not interfere among themselves. Each category comprised six exemplars; no two exemplars began with the same first two letters to avoid interference during the retrieval-practice phase.

Operation span task (OSPAN)

As a measure of WMC, we used the Italian version of the operation span task (OSPAN; Conway et al., 2005). This task contained 15 blocks of trials. The number of trials for each block varied from 2 to 6, for a total of 60 trials. Within each trial, participants first solved an arithmetic problem and then remembered one-syllable word, for example, “(6 × 5) + 1 = 31? DOLL”. Participants first viewed the arithmetic problem and then moved on to the next page where a solution appeared on the screen. On this page, they indicated whether the presented solution was correct or incorrect and subsequently read a word before moving on to the next trial. At the end of each block, participants were asked to remember and type on the screen all the words in the exact order of presentation. OSPAN scores were computed by calculating the proportion of correctly recalled words in the correct order position for each block.

NfCC

Participants’ NfCC was measured with the same Italian version of the Revised NfCS (Pierro & Kruglanski, 2005) used in Study 1. In the present sample, the reliability (Cronbach’s alpha) of the Revised NfCS scale was satisfactory at .77.

Results

Retrieval practice

Retrieval rate of retrieved items (Rp+ items) was on average 88% (SD = 1.40), suggesting that the practice phase was successful. Moderated multiple regression analyses were conducted to test whether our independent variables (i.e., retrieval-practice repetitions, NfCC, and OSPAN) exerted a general effect on retrieval practice. As expected, neither the main effects of OSPAN, NfCC, and retrieval-practice repetitions, nor the interaction effects were significant (all ps > .05).

Facilitation effect

To determine whether the retrieval practice produced the expected facilitation effect, we conducted a 1-way ANOVA with item type (Rp+ and Nrp) as a repeated measures factor. This analysis revealed a significant effect of item type, Rp+ = 73.85%, SD = 19.31; and Nrp = 43.22%, SD = 13.47; F(1, 93) = 208.16, p < .001, η_p² = .69. Thus, as expected, retrieval-practice task produced the facilitation effect.

Again, to control for the possibility that our independent variables (i.e., retrieval-practice repetition, NfCC, and OSPAN) exerted a general impact on the facilitation effect we computed the facilitation effect by subtracting the recall percentage of Rp+ items from the recall percentage of Nrp items [facilitation effect = (Rp+) − (Nrp)], and we performed a moderated multiple regression analysis. Neither the main effects nor the interaction effects between these variables were significant (all ps > .05).

RIF

To determine whether the retrieval practice produced the expected RIF effect, we conducted a 1-way ANOVA with item type (Nrp and Rp−) as a repeated measures factor. Results revealed a significant effect of item type (Nrp = 43.22%, SD = 13.47; and Rp− = 34.93%, SD = 18.42), F(1, 93) = 38.57, p < .001, η_p² = .29. Therefore, as expected, retrieval-practice task produced the RIF effect. We then computed the RIF effect by subtracting the recall percentage of Rp-items from the recall percentage of Nrp items [RIF effect = (Nrp) − (Rp−)]. As in Study 1, our predictions regarding RIF as a function of retrieval-practice repetitions (contrast coded: two retrieval-practice repetitions = −1; four retrieval-practice repetitions = 1), NfCC, and OSPAN was tested with moderated multiple regression analysis. NfCC and OSPAN were mean-centered (Aiken & West, 1991).

This analysis revealed a significant main effect of retrieval-practice repetitions (β = .29, t = 2.96, p < .01), thereby indicating that the more individuals were asked to retrieve some items, the more related items were likely to be forgotten. This result is consistent with previous findings (Johnson & Anderson, 2004; Levy et al., 2007; Parker & Dagnall, 2009; Storm, Bjork, & Bjork, 2008), and it validates our manipulation of task difficulty. All other main effects and the two-way interactions were nonsignificant (all ps > .05). Of greatest importance, the three-way interaction between retrieval-practice repetition, need for closure, and OSPAN was significant, β = −.24, t = −2.25, p < .05. These findings are illustrated via the predicted mean values shown in Figure 2A and 2B.

Figure 2A.

Retrieval-induced forgetting as a function of OSPAN score and need for cognitive closure in four retrieval-practice repetition condition (Study 2).

Figure 2B.

Retrieval-induced forgetting as a function of OSPAN score and need for cognitive closure in two retrieval-practice repetition condition (Study 2).

To further understand the nature of this 3-way interaction (Aiken & West, 1991), we conducted a simple interaction analysis. It revealed that the 2-way interaction of OSPAN score by NfCC was significant in the predicted direction in the two retrieval-practice repetition conditions (β = .34, t = 2.27, p < .05) and was nonsignificant in the four retrieval-practice repetition conditions (β = −.14, t = −.93, p > .3). Therefore, when retrieval practice was repeated two times, RIF effect was predicted by the interaction of participants’ WMC (i.e., OSPAN score) and motivation toward closure (NfCC; see Figure 2A), whereas when retrieval practice was repeated four times, RIF effect was not affected by participants’ WMC and motivation toward closure (see Figure 2B).

Moreover, simple slope analyses conducted to analyze the two-way interaction (OSPAN capacity and need for closure) for participants in the two-repetitions condition revealed, as predicted, a significant and positive relationship between RIF effect and NfCC for participants relatively high in OSPAN (1 SD above the mean: β = .63, t = 2.45, p < .05); this relationship was not significant for participants relatively low in OSPAN (1 SD below the mean: β = −.07, t = −.38, p > .7). Overall then, in the two repetition conditions, the higher the participants are in the OSPAN and NfCC the more they appear to inhibit the competing items, showing the RIF effect.

Discussion

Results of Study 2 provide support for our model: When participants’ retrieval-practice phase consisted of four trials (vs. two trials), rendering inhibition easier to accomplish, they exhibited a more pronounced RIF effect. More importantly, within the two retrieval-practice condition, participants produced a greater RIF effect when they had larger WMC (OSPAN task) and higher NfCC. These predictions were confirmed with well-known brand names and product categories, suggesting the relevance of our theoretical analysis to everyday real-world memories, with important implications for consumer memory research.

Thus, we found that prior retrieval of some brands from a product category impaired the memory of competitor brands. Such impairment was contingent on the relation between individuals’ driving force and their restraining force. When the restraining force was low because inhibition was easy to accomplish (i.e., in the four retrieval trials condition), one’s driving force did not need to be strong to inhibit brands from the same product categories. However, when retrieval practice of some brands did not afford an easy brands-related forgetting (i.e., two retrieval-practice repetitions), the restraining force was of sufficiently high magnitude and individuals with adequate amount of cognitive resources (those with high scores on the OSPAN task) that were also highly motivated to recruit them (i.e., those high on the NfCC) succeeded in inhibiting the competing brands, thereby demonstrating the RIF.

General Discussion

The phenomenon of RIF has fascinated cognitive researchers over the past two decades (M. C. Anderson, 2003). Mounting evidence has indicated that the RIF is based on an inhibition of interfering items, and that such inhibition represents a demanding, resource intensive, process (Koessler et al., 2009; Ortega et al., 2012; Romàn et al., 2009). The present research contributes further to the understanding of the RIF by exploring the heretofore neglected motivational aspect underlying successful inhibition. We reasoned that overcoming the difficulties that the inhibitory task imposes requires a willingness to expend the energy that expresses an individual’s goal or purpose that can vary in magnitude across situations. Specifically, we assumed that the mere availability of resources is insufficient for the RIF, and that one also needs to be motivated to recruit and invest those resources in the inhibitory activity that underlies this phenomenon.

To explore these matters, we grounded our analysis of the RIF in CET proposed by Kruglanski et al. (2012). The CET conceptualized the dynamics of motivated cognition (represented by the RIF and other cognitive activities) in terms of a force field wherein a driving force “faces off” with a restraining force. The former force is determined by the degree of motivation to perform the cognitive activity (inhibition in this case) and the pool of mental (attentional) resources at the individual’s disposal. According to the CET, the greater one’s motivation the greater the proportion of available resources recruited and potentially invested in the cognitive activity. The actual amount of resources invested is determined by a restraining force, which varies as a function of the demandingness or difficulty that the activity presents.

In line with the foregoing analysis, the present research varied three essential parameters identified in the CET. These are (a) magnitude of the motivation to inhibit the competing memories operationalized here as the NfCC, (b) availability of resources manipulated via circadian matches and mismatches in Study 1 and assessed via the OSPAN task in Study 2, and (c) difficulty of the inhibitory activity manipulated via the number of retrieval practices allowed for the participants.

The results of our two studies offered consistent support for our hypotheses. In Study 1, where difficulty of the inhibitory task was uniformly high, we found that the RIF effect was obtained only where the interfering items were in a high taxonomic category, that is, where they created significant distraction (attentional competition), warranting their inhibition (replicating the competition dependence assumption of RIF, M. C. Anderson et al., 1994). Furthermore, a significant amount of RIF appeared to be greater where a high degree of the need for closure was coupled with a relatively ample presence of cognitive resources (i.e., in the circadian match vs. mismatch conditions).

Our second study provided additional evidence for the CET analysis. It replicated the results of Study 1 in a condition where the inhibition difficulty was assumed to be relatively high (i.e., in the two practice retrievals condition), but not in a condition where the inhibition difficulty was assumed to be low (i.e., in the four practice retrievals condition). As in Study 1, where the inhibition difficulty was high, RIF appeared to be greater where high NfCC was coupled with a high degree of cognitive resources. In other words, consistent with the CET, the mere availability of resources did not suffice to produce the RIF effect; instead, motivation was needed to appropriately draw on those resources. It is noteworthy that our two studies differed methodologically in a number of ways including the operationalization of cognitive resources and the contents of the memory items used as the stimulus materials. That both experiments produced results consistent with our theoretical analysis provides convergent evidence for its validity.

It is also of interest that the present findings are highly consistent with prior RIF research, and they replicate the important findings as to the role of taxonomic frequency of interfering items (M. C. Anderson et al., 1994) and the effect of retrieval-practice trials on RIF (Johnson & Anderson, 2004; Levy et al., 2007; Storm et al., 2008). This consistency with past relevant research is encouraging in two ways: First, it attests to the replicability and robustness of the RIF phenomena across cultures, methods, and materials. Second, it indicates that the novel contribution of the present work that highlights the role of motivation in the RIF and its interactive relation with cognitive resources addresses the same phenomenon addressed by our predecessors. In general, then, our findings imply that the RIF is governed by similar principles and factors that regulate motivated cognition more generally.

Last but not least important, it is of interest to consider how our findings bear on personality and social psychological phenomena. It appears that given sufficient resources, persons who are high on the need for closure (whether as a stable personality trait or because of situational conditions) should exhibit a variety of memory biases by focusing on momentarily (or chronically) accessible category items (comparable with the Rp+ items in the Retrieval-Practice Paradigm). For example, they might remember their successes more than their failures, as well as stereotypic traits about persons (e.g., related to their gender, ethnicity, or age) more so than other less accessible details.

The combined effects of resources and motivation (e.g., need for closure) in sharpening memory for given categories of material (as reflected by the RIF effect) may have significant interpersonal consequences where the same individuals have different memories of seemingly the same event (Hastorf & Cantril, 1954) leading to disagreements and potential conflicts.

Finally, inhibition of interfering items could mean restriction of one’s memory search and false confidence in items that for some reason were highly accessible to the individual. This might limit individuals’ flexibility in interpersonal interaction and reduce their ability to “think on their feet” as it were.

It would be also of interest to explore alternative components of individuals’ restraining force (Kruglanski et al., 2012), as it may affect individuals’ ability to inhibit interfering item and hence retrieve the targeted items from memory. Such components include the press of alternative goals as well as individuals’ stable degree of cognitive conservationism (e.g., low need for cognition or cognitive miserliness). If our theoretical analysis is correct, these motivational aspects of persons and situations should have significant, and heretofore unrecognized, impact on everyday remembering and forgetting that could be profitably explored in future research.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Notes

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