An Evaluation of Nonclinical Dissociation Utilizing a Virtual Environment Shows Enhanced Working Memory and Attention

Abstract

Dissociation is a mental process resulting in the disruption of memory, perception, and sometimes identity. At a nonclinical level, only mild dissociative experiences occur. The nature of nonclinical dissociation is disputed in the literature, with some asserting that it is a beneficial information processing style and others positing that it is a psychopathological phenomenon. The purpose of this study was to further the understanding of nonclinical dissociation with respect to memory and attention, by including a more ecologically valid virtual reality (VR) memory task along with standard neuropsychological tasks. Forty-five undergraduate students from a small liberal arts college in the northeast participated for course credit. The participants completed a battery of tasks including two standard memory tasks, a standard attention task, and an experimental VR memory task; the VR task included immersion in a virtual apartment, followed by incidental object-location recall for objects in the virtual apartment. Support for the theoretical model portraying nonclinical dissociation as a beneficial information processing style was found in this study. Dissociation scores were positively correlated with working memory scores and attentional processing scores on the standard neuropsychological tasks. In terms of the VR task, dissociation scores were positively correlated with more false positive memories that could be the result of a tendency of nonclinical highly dissociative individuals to create more elaborative schemas. This study also demonstrates that VR paradigms add to the prediction of cognitive functioning in testing protocols using standard neuropsychological tests, while simultaneously increasing ecological validity.

Introduction

Dissociation is a mental process resulting in the disruption of memory, perception, and sometimes identity.¹ Dissociation can be understood as existing on a spectrum, ranging from a nonclinical level to a clinically disordered level. Dissociation at a nonclinical level (often referred to as dissociative tendencies) is apparent in all individuals, with dissociative experiences ranging from “highway hypnosis,” the tendency to drive for long stretches of time without being consciously aware of doing so, to more extreme experiences such as finding a note that one recently wrote and retaining no memory of writing the note. The origin of dissociative tendencies is heavily debated in the literature, with the two predominant theories arguing in favor of either an enhanced information processing style unrelated to psychopathology, or betrayal trauma and the subsequent pathological detachment of cognitive environments.

The Betrayal Trauma Theory of Jenifer Freyd² asserts that dissociation at both a clinical and a nonclinical level is the result of mental trauma and is therefore psychopathological in nature. Freyd's theory argues that dissociative experiences are the result of traumatic childhood incidents, suggesting that dissociation is utilized to maintain a necessary system of attachment after betrayal. Although individuals suffering from betrayal and trauma typically subsequently distance themselves from interaction with the individual who caused them to suffer, it is evolutionarily unwise for those suffering betrayal to distance themselves from an individual whom they psychologically and physically depend on for survival. Consequently, the suffering individual must adopt an alternative mechanism for dealing with the betrayal. This results in the child blocking the abuse from his or her mind, by creating particular cognitive environments marked by high levels of divided attention; this anomaly is essentially dissociation. Thus, Freyd's Betrayal Trauma Theory posits that dissociation is inherently associated with psychological disorder and inhibited cognitive functioning, irrespective of the level of intensity.

The Construction Hypothesis of De Ruiter et al.³ posits an alternative explanation for dissociative tendencies. The Construction Hypothesis' primary supposition is that nonclinical dissociation is fundamentally unrelated to trauma and psychopathology, and rather can be understood as a cognitive trait which fluctuates naturally in the population. The Construction Hypothesis asserts that dissociative tendencies reflect an enhanced information processing style, associated with augmented attention and memory capabilities. The mechanisms proposed for the Construction Hypothesis highlight the tendency of high nonclinical dissociators to construct more vivid conscious experiences. This elaborative processing style can lead to facilitated memory, but may also produce an increase in false memories. One key qualification that the Construction Hypothesis makes is that for the enhanced cognitive capabilities of high dissociators to be recognized by experimenters, the task given must be adequately complex and intriguing; if the task is too mundane, high dissociators may be more likely to focus their enhanced attentional abilities on something more stimulating, such as daydreaming. In conclusion, the Construction Hypothesis suggests that nonclinical dissociation is associated with enhanced cognitive functioning.

Consistent with the reasoning of the Betrayal Trauma Theory, there has been a fair amount of research suggesting that nonclinical dissociation is associated with deficits in attention and memory. Freyd et al.⁴ evaluated attention in nonclinical dissociators by utilizing the standard color-word Stroop paradigm without modification,⁵ in which participants must selectively attend to one aspect of the presented stimuli (color) while ignoring another aspect of the stimuli (word). High dissociators displayed a significantly greater level of Stroop interference than low dissociators, suggesting that high dissociation is associated with deficits in selective attention. Amrhein et al.⁶ compared low with high dissociators, utilizing an extensive battery of cognitive tasks, and reported that high dissociators showed cognitive deficits compared to low dissociators. Specifically, the high dissociator group had significantly poorer scores on spatial working memory and delayed recall for logically associated words, and a significantly higher number of false positive errors on a verbal learning and memory test.

In contrast to these findings, there is also a substantial amount of literature which suggests a positive relationship between nonclinical dissociation and cognitive capabilities such as attention and memory. In a study evaluating attentional characteristics of high and low nonclinical dissociators, De Ruiter et al.⁷ employed both behavioral and neurophysiological measures. Specifically, reaction time and event-related potentials (ERPs) were evaluated with respect to the participant's ability to quickly attend to presented stimuli. The study found that, on average, high dissociators displayed enhanced attentional abilities compared with low dissociators. With respect to memory, Veltman et al.⁸ demonstrated increased verbal working memory for high dissociators compared with low dissociators. This study utilized neurophysiological measures, demonstrating enhanced activation for several neural networks associated with working memory for high dissociators compared with low dissociators during their completion of the n-letter-back and Sternberg tasks.

Although most memory research has been done using paper and pencil tasks, there is a new era of cognitive research utilizing cutting edge technology.⁹ Virtual reality (VR) and virtual environments (VEs) have become quite popular with many researchers who wish to extend their explorations beyond the limits imposed by real world experimentation, including such variables as time and cost.¹⁰ In terms of cognitive research, there are now a number of studies in the literature which suggest that VEs can be successfully utilized to understand memory processes.^9,11–15

For example, Brooks et al.¹⁶ and Hahm et al.¹⁷ utilized VR paradigms to study whether active versus passive navigation has an effect on memory. Active navigation was defined as using a joystick to control one's own VE, whereas passive navigation was defined as observing the changes in one's VE while having no control over said changes. Both studies found that active navigation allowed for superior recollection than did passive navigation, suggesting that the active involvement in one's environment may provide for a more ecologically valid memory test than typical paper and pencil tests.

The focus of the present study was to further examine the relationship between nonclinical dissociation and cognitive functioning, by utilizing standard neuropsychological tasks and an experimental, more ecologically valid, VR task. The hypotheses of this study followed the logic of the Construction Hypothesis, considering its widespread support in the recent literature. First, it was hypothesized that there would be a positive correlation between dissociation scores and working memory ability. Second, it was hypothesized that there would be a positive correlation between dissociation scores and attentional ability. Third, it was hypothesized that there would be a positive correlation between dissociation scores and false memory scores. As a last qualification, it was hypothesized that enhanced memory for high dissociators would be revealed for the more difficult or stimulating memory tasks in this study.

Method

Participants

Forty-eight undergraduate students from Saint Anselm College in Manchester, NH were recruited for this study. The final nonclinical sample included 45 participants (males=21, females=24), as 2 participants were excluded for depression and 1 participant for failure to complete all tasks according to instructions. The majority of participants were Psychology majors with ages ranging from 18 to 21 years. All participants reported their race as Caucasian.

Materials

Digit Span (forward and backward)

The Wechsler Digit Span Task was utilized in this study as a measure of verbal working memory. This test requires the examiner to verbally present digits at a rate of one per second. The forward test requires the participant to repeat the digits verbatim. The backward test requires the participant to repeat the digits in reverse order. The number of digits increases by one until the participant consecutively fails two trials of the same digit-span length.¹⁸

NeuroVR Incidental Memory Task

This VR task was developed using NeuroVR 1.5¹⁹ for use on a desktop computer. The VE was a virtual apartment, containing 24 objects, very similar in construction to the VR task of Brooks et al.¹⁶ For our NeuroVR task, the final 24 objects were selected from familiarity ratings of 38 objects provided by 50 judges. The objects were rated on a Likert scale from 1 to 7 for familiarity, defined as how likely one would be to see the object in an apartment (1=very unlikely, 7=very likely). Satisfactory reliability for familiarity level was achieved (coefficient α>0.80). All of the six items selected for each room (i.e., bedroom, bathroom, kitchen, and living room) were similar in overall familiarity levels. Specifically, a series of dependent t tests revealed no mean differences across rooms: bedroom (M=6.1, SD=0.65), bathroom (M=63, SD=0.44), kitchen (M=6.3, SD=0.84), living room (M=6.1, SD=0.75).

Participants utilized an eMagin Z800 3DVisor head mounted display for immersion in the VE and a Logitech Dual Action gamepad for navigation. This was an implicit memory task, given that participants were asked to explore the apartment for 2 minutes without explicit instructions involving later recall. In fact, the same instructions set forth in Brooks et al.¹⁶ were utilized in this study. Memory for objects in the VE was tested immediately after completion. Participants were given a template of the VE, with one object displayed in each of the four rooms, and were asked to write in as many additional objects as they could remember from the VE, in their respective rooms. The NeuroVR Incidental Memory Task (NeuroVR IMT) was scored for total objects recalled with subscores for false positives and correct recalled. Correct recalled also had subscores for correct location and incorrect location.

Simulator Sickness Questionnaire

The Simulator Sickness Questionnaire (SSQ) was developed by Kennedy et al.²⁰ to quantify simulator sickness. The SSQ was utilized to screen for potential simulator sickness invoked by the VR task. Simulator sickness symptomology was considered evident if a participant endorsed a severe response for any of the 27 items on the SSQ. SSQ post-test surveys did not reveal that any participants reported symptomology.

Video Game Experience Questionnaire

The Video Game Experience Questionnaire (VGEQ) includes 10 items related to video game experience. It has been used in research considering the impact of video game history on visuo-spatial skills.²¹ Current level of computer gaming, defined as whether one is involved in computer gaming daily (4), weekly (3), monthly (2), yearly (1), or never (0), was included in our analyses.

Beck Depression Inventory II

The Beck Depression Inventory Second (BDI-II) Edition is a 21-item self-report instrument intended to assess the existence and severity of symptoms of depression.²² Participants are asked to rate on a 4-point scale how they may have felt or behaved over the past 2 weeks. BDI-II scores of 29 or higher resulted in participant exclusion from our final sample (n=2).

Corsi (forward and backward)

The Corsi-block tapping task measures spatial working memory, requiring the participant to watch the researcher tap out a sequence of blocks configured on a board (nine total blocks) and repeat this order by tapping on the same order of blocks. The backward test requires the participant to repeat the block sequence in reverse order. The number of blocks increases by one until the participant consecutively fails two trials of the same spatial span length.²³

Trail Making Test (A and B)

The Trail Making Test (TMT) was developed by Reitan²⁴ to measure attention, speed, and mental flexibility. Part A requires the participant to connect, making pencil lines, 25 encircled numbers in proper ascending order, measuring the participant's attentional processing speed. Part B requires the participant to connect 25 encircled numbers and letters in alternating order, measuring processing speed and flexibility in alternating between stimuli.

Demographic survey

The demographic survey included items for race, ethnicity, gender, age, and major.

Dissociative Experiences Scale II

The Dissociative Experiences Scale II (DES-II) is a 28-item self-report questionnaire which quantifies level of dissociation. In 1993, Carlson and Putnam revised the DES, keeping the same 28 questions, but replacing the analog answer scale with a much simpler, 11-point Likert scale. The DES-II has been shown to have good test-retest reliability (r=0.84) and strong construct validity.²⁵

Procedure

The study took place in the NeuroVR testing room at Saint Anselm College. Each participant completed an informed consent form before beginning the testing session. The testing session took approximately 45 minutes and the following tests were administered in this order: Digit Span (forward and backward), NeuroVR IMT (including SSQ-pre/post versions), VGEQ, BDI-II, Corsi (forward and backward), TMTs (versions A and then B), Demographic Survey, and finally DES-II. Upon completion of the study, participants were fully debriefed regarding the purpose of the study and the implications of the results for the field.

Results

Demographic variables

The mean DES-II score of all participants was 11.19 (SD=7.87). There was no significant gender difference for DES-II scores, p>0.05. Current level of computer gaming was not significantly related to DES-II scores, p>0.05. However, depression scores were significantly correlated with DES-II scores, r(43)=0.35, p=0.02. Table 1 includes descriptive statistics for all of the demographic and cognitive functioning variables for the entire sample.

Table 1.

Mean and Standard Deviation for All Demographic and Cognitive Functioning Variables for the Entire Sample (n=45)

Variable	M	SD
Dissociative Experiences Scale II	11.19	7.87
Current Computer Gaming Level	1.91	1.35
Beck Depression Inventory II	5.05	4.51
Digit Span (forward)	10.76	1.93
Digit Span (backward)	6.58	1.96
Corsi (forward)	8.78	1.72
Corsi (backward)	7.64	1.89
Trail Making Test: A	19.16	6.18
Trail Making Test: B	48.96	28.12
NeuroVR IMT: Total Recalled	7.82	3.39
NeuroVR IMT: False Positives	1.49	1.69
NeuroVR IMT: Correct Recalled	6.33	2.62
NeuroVR IMT: Correct Location	6.18	2.57
NeuroVR IMT: Incorrect Location	0.20	0.59

Cognitive functioning

Although DES-II scores were significantly correlated with depression scores, depression scores were not significantly correlated with any cognitive variables in this study. For the neuropsychological tests, higher DES-II scores were associated with better performance on the Corsi (backward), r(43)=0.29, p=0.03, TMT A, r(43)=−0.33, p=0.01, and TMT B, r(43)=−0.31, p=0.02. No significant relationships between DES-II scores and Digit Span (forward or backward) scores, or Corsi (forward) scores were observed.

All five of the NeuroVR IMT scores were correlated with DES-II scores. Only false positive scores were significantly correlated with DES-II scores, r(43)=0.28, p=0.03, such that higher DES-II scores were associated with more false positives.

A stepwise multiple regression analysis was conducted to determine which cognitive functioning scores predicted DES-II scores. Regression results indicated that three predictors explained 31.0% of the variance (R²=0.31, R²_adj=0.26, F(3, 41)=6.12, p=0.002). It was found that TMT A scores predicted DES-II scores (β=−0.37, p=0.007), as did correct location (β=−0.37, p=0.008), and false positive scores (β=0.34, p=0.015).

Discussion

The literature on nonclinical dissociation is far from conclusive. It is essentially split as to whether nonclinical dissociation is associated with either facilitated or impaired cognitive functioning. Two major theories, the Construction Hypothesis³ and the Betrayal Trauma Theory,² posit contradictory theoretical models, portraying nonclinical dissociation as either beneficial or psychopathological. The present study sought to further the understanding of nonclinical dissociation with respect to memory and attention, by including a more ecologically valid memory task along with standard neuropsychological tasks.

In terms of cognitive functioning, memory scores on the neuropsychological tests indicated higher visuo-spatial working memory scores with increasing dissociation scores. This finding adds to research by De Ruiter et al.²⁶ demonstrating enhanced verbal working memory for high compared to low dissociators. Higher working memory scores in this study were achieved for one of the most demanding measures, that is, backward performance on the Corsi. This is consistent with our interpretation of the Construction Hypothesis' assertion that nonclinical dissociators will show enhanced performance when the task is sufficiently challenging and engaging.

It is also consistent with the Construction Hypothesis that higher dissociative scores were related to faster performance on the TMTs (A and B). Previous cases of enhanced attention for high nonclinical dissociators, in terms of reaction time and ERPs, have been reported by De Ruiter et al.⁷ Further, in a clinical sample of veteran participants with dissociative disorders compared to controls, the disordered individuals displayed slower scores for the TMT B.²⁷ Thus, nonclinical dissociation confers enhanced attentional processing; however, this trend is not observed when considering the clinical disorder.

Enhanced attentional processing with higher dissociative scores should be considered along with our finding of more false positives on the NeuroVR IMT in our study. This is not the first study to report higher false positives with higher dissociation scores, as Candel et al.²⁸ and Amrhein et al.⁶ have noted similar results. However, this is the first study to utilize a VE to challenge participants to correctly recall object locations in a more ecologically valid task. It is important to consider that the instructions for the NeuroVR IMT did not require participants to explicitly encode object location; therefore, their incidental memory for the task could have been mediated by how much attention they actually focused on the objects in the VE, versus on competing thoughts while navigating. Given that high dissociation scores were associated with more false positives, it is possible that reliance on more elaborative schemas for an apartment could have produced these results. This is consistent with the Construction Hypothesis.³ It also adds to the literature on Schema Theory,²⁹ which suggests that implicit versus explicit components of the task need to be considered relative to understanding the nature of the false positives.

Each of the aforementioned findings supports the assumption that nonclinical dissociation is associated with cognitive functioning scores from both standard neuropsychological tests and the NeuroVR IMT. Further, the best set of predictors for DES-II scores includes scores from the NeuroVR IMT along with one standard neuropsychological test (i.e., TMT A), suggesting that scores from a VR-based task such as the NeuroVR IMT add to the prediction of DES-II scores. Therefore, testing protocols with standard neuropsychological tests, along with ecologically valid tests of cognitive functioning created using NeuroVR, can help us better understand mental processes and behavior.^30,31

It is important to note that the findings from this study are limited to understanding nonclinical dissociation in a sample of college-aged students, where it was not possible to utilize DES-II cutoff scores, as reviewed by Giesbrecht and colleagues³² in their meta-analysis of the literature on dissociative thinking. Future research conducted with a much larger and more heterogeneous sample would permit identification of low and high dissociation subgroups and comparisons between these groups relative to their cognitive functioning. At the present time, however, we have established that nonclinical dissociation is positively associated with enhanced cognitive functioning in college-aged students.

In conclusion, this study has established that testing memory in VEs expands our understanding of cognitive functioning. An important new direction regarding dissociation and VEs would be to consider other manipulations involving sound or smell to examine whether false positives continue to be found with greater frequency among high nonclinical dissociators. Further, it will be important to add avatars to VEs to increase their ecological validity when evaluating cognitive functioning not only relative to dissociative thinking but also other cognitive styles.

Footnotes

Acknowledgments

Thank you to all the participants. Also to Dr. Maria McKenna and Hannah Watkins for their editorial assistance, and to Dr. Adam Wenzel for his help throughout the study.

Disclosure Statement

No competing financial interests exist.

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