Validating a brief measure of the Zimbardo Time Perspective Inventory

Abstract

Zimbardo and Boyd (1999) developed the 56-item Zimbardo Time Perspective Inventory (ZTPI). It has become the leading measure used in the study of subjective time. In this article, we report an abbreviated ZTPI that only includes 15 total items (SZTPI-15). We tested the psychometric characteristics of the SZTPI-15 by focusing on: (a) convergent and discriminant validity, (b) external validity, (c) test–retest reliability and (d) self-peer ratings. On the basis of these tests, the results demonstrated that the short version was less reliable than the standard ZTPI but showed impressive psychometric convergence with the standard ZTPI.

Keywords

time perspective brief measures personality well-being

Researchers are looking for ways to make data collection more time-efficient. One obvious way is by creating shorter scales. Interestingly, what was a short measure in the past is now considered a long measure. For example, The Big Five Inventory (BFI; John et al., 1991) was considered a short instrument when it was initially developed because it only contained 44 items and required 5 minutes to complete. However, the demand for even shorter scales gave rise to the 10-item Big Five Inventory (BFI-10; Rammstedt and John, 2007), which requires a fraction of the time to complete. Because longer measures can be used to measure separate dimensions of a construct, they are preferred when time and resources are not a concern. However, short scales provide several important distinct advantages.

For a society that is increasingly pressed for time, a short scale ‘eliminates item redundancy and therefore reduces the fatigue, frustration, and boredom associated with answering highly similar questions repeatedly’ (Robins et al., 2001, p. 152). First, because brief scales place less burden on the participants, they can be used across various research contexts (e.g. experience sampling and longitudinal studies; see Robins et al., 2001). Second, researchers often wish to include a variety of instruments for measuring different predictors of a specific outcome (Richins, 2004) – it is more efficient to measure various predictors when all the scales are brief. Third, longer questionnaires decrease response rates in non-captive audiences taken from the general population, as compared to typical college students completing surveys in class for credit (McCarty et al., 2006).

In sum, there are obvious advantages to a short measure, and its instrumental value is well accepted by many researchers. The difficulty in adopting shorter versions of previously validated measurement indices is ensuring that the discriminating features of the original measure remain largely intact. In the present study, we turn our attention to time perspective and aim to validate a brief measure of the Zimbardo Time Perspective Inventory (ZTPI; Zimbardo and Boyd, 1999). We believe there is a need to develop a short ZTPI because (a) the ZTPI has become a central instrument in the study of time perspective, (b) it has implications in a wide range of research areas and (c) and a short scale provides researchers the ability to measure each of the ZPTI’s subscales without overburdening participants. Below, we summarize these points and provide a synthesis for our reasoning.

The development and implications of time perspective

Within the subjective time paradigm, the study of an individual’s time perspective is one of the more important research areas (Boniwell, 2005). The earliest definition of the subjective time perspective was provided by Lewin (1951, p. 75) as: ‘the totality of the individual’s views of his psychological future and psychological past existing at a given time.’ McGrath and Kelly (1986) identified up to 211 different ways to measure and assess time perspective developed since the Lewin measurement. The popular earlier approaches to measure time perspective were: (a) largely graphical, (b) story-based or (c) projective tests (Barndt and Johnson, 1955; Kastenbaum, 1961; Knapp and Garbutt, 1958). These approaches had two limitations: (a) the psychometric properties of these methods were inferior and (b) they tended to focus on only one time perspective (and usually the future orientation; see Bond and Feather, 1988; Strathman et al., 1994; Zaleski, 1996; Zuckerman, 1994). For these reasons, the Zimbardo Time Perspective Inventory (ZTPI; Zimbardo and Boyd, 1999) was developed, with strong psychometric properties, in order to capture the breadth of multiple time orientations within a single instrument.

The ZTPI consists of five subscales (past positive, past negative, present hedonistic, present fatalistic and future) and represents an individual’s relation with time as a non-conscious process whereby individuals parcel their personal and social experiences into temporal categories (Boyd and Zimbardo, 2005). Since its development, many studies have used the ZTPI as the main measure of time perspective and have demonstrated the relations the ZTPI has with multiple behavioural and psychological outcomes (Boniwell and Zimbardo, 2004).

For example, a recent study demonstrated that time perspectives are closely associated with personality traits (Dunkel and Weber, 2010): extraversion was positively correlated to the past positive and present hedonistic time perspectives, while being negatively correlated to the past negative time perspective. Also, neuroticism was positively correlated with having a past negative time perspective and negatively correlated to having a past positive time perspective. The relationships between time perspectives and subjective well-being have also been specified. For instance, past negative is associated with lower life satisfaction and happiness, whereas past positive showed opposite correlations with these two outcomes (Boniwell et al., 2010). More recently, Zhang and Howell (2011) extended these studies to show that time perspective is an important mechanism for explaining the personality and subjective well-being link. Specifically, they found that time perspective accounted for an additional 13.7% of the variance in life satisfaction beyond personality traits, whereas personality traits accounted for an additional 4.4% of the variance in life satisfaction beyond time perspective. More importantly, their mediation models found that time perspective partially accounted for the personality and life satisfaction relationship. Together, time perspectives are related both to different personality traits and to psychological well-being, and they play a substantial role in explaining the personality-subjective well-being relation.

Missing information in studying all time perspectives

Given the important implications of time perspectives, it is important for researchers to investigate the relation of each time perspective with the outcomes of interest. Most studies on time perspectives have not used all five subscales. For example, Zimbardo et al., Boyd (1997) found that present hedonism is a predictor of risky driving, and Adelabu (2007) discovered that present hedonism is associated with lower academic achievement in a sample of African American adolescents. On a similar note, Kruger et al. (2008) found that the present and future time perspectives fully mediated the relationship between the positive and negative aspect of student’s neighbourhood social environment and interpersonal aggression. Similar to these studies, more researchers have used three time perspective or fewer in their research (Epel et al., 1999; Harber et al., 2003; Luyckx et al., 2010). This focus on a few dimensions leaves open the possibility that other time perspectives might also influence the results. Indeed, the focus on only the present and future time perspectives was the first limitation Lens and his colleagues (2010) acknowledged in their study on time perspective and identity formation.

Before Zimbardo and Boyd (1999) developed their five-dimension, 56-item Zimbardo Time Perspective Inventory (ZTPI), Zimbardo and colleagues developed The Stanford Zimbardo Time Perspective Inventory (Zimbardo et al., 1997). The 1997 Zimbardo Time Perspective Inventory contained only the present fatalism, present hedonism and future subscales and lacked the past positive and past negative subscales, which are included in the present ZTPI. D’Alessio et al. (2003) utilized this earlier three-dimensional time perspective inventory when they developed their short form of the Stanford Zimbardo Time Perspective Inventory. As a result, their short form failed to address the past positive and past negative dimensions.

Recent research, however, found that the two past dimensions have important implications for personality traits and subjective well-being (Dunkel and Weber, 2010; Zhang and Howell, 2011). Also important is the fact that the lack of the two past dimensions prohibits researchers from studying the balanced time perspective construct (BTP), which requires scores from all five subscales and is hypothesized to be the optimal perspective on psychological time (Zimbardo and Boyd, 1999; Boniwell et al., 2010). Thus, the absence of the past dimensions in D’Alessio et al. (2003) is an important gap that needs to be filled. Consequently, we validated a short form of the most updated, five-dimension version the ZTPI (Zimbardo and Boyd, 1999), which includes the two past dimensions.

We note that it is possible that researchers have neglected to measure all five time dimensions because they are interested in the relationship between one or more specific time perspectives and the outcome(s) of interest. However, another possibility is that the current 56-item ZTPI is relatively lengthy compared to other widely used individual differences scales (Satisfaction with life is 5 items, Diener et al., 1985; Subjective happiness is 4 items, Lyubomirsky and Lepper, 1999). Thus, the development of a short ZTPI would allow researchers to employ all five time perspectives while not unduly burdening respondents. Further, it is our goal that a short ZTPI would allow researchers to further investigate the unique associations that each time perspective may have with its outcomes.

The current study

Because previous studies have found consistent relationships between time perspectives and personality traits, life satisfaction, and positive and negative affect (Boniwell et al., 2010; Dunkel and Weber, 2010; Zhang and Howell, 2011), we administered these scales in addition to the ZTPI to provide validity for the short ZTPI. Also, we added informant reports because they provide strong consensus and self–other agreement in support of our validation and are in line with the call for more use of informant reports (Schneider and Schimmack, 2009).

Method

Participants

We recruited six samples. The first sample consisted of 726 participants (50.4% females; mean age = 31.63, SD = 11.83) recruited from San Francisco State University (SFSU) and various social networking sites (e.g. Mturk, Facebook, Craigslist). The second, third and fourth samples consisted of 641 (49.8% females; mean age = 25.28, SD = 9.35), 279 (53% females; mean age = 23.38, SD = 7.78) and 143 (84.6% females; mean age = 25.41, SD = 10.31) participants from SFSU. The fifth sample consisted of 360 participants (54.3% females; mean age = 24.63, SD = 9.78) from SFSU, websites that host psychology studies (e.g. www.socialpsychology.org) and social networking sites. Finally, a sixth sample of 76 participants (75% females; mean age = 25.26, SD = 7.37) was recruited from an undergraduate psychology course at SFSU.

Measures

Zimbardo time perspective inventory

We measured time perspective using the ZTPI developed by Zimbardo and Boyd (1999). The ZTPI is a 56-item questionnaire and each time perspective is assessed using a 5-point scale (1 = very untrue of me, 5 = very true of me). Nine items measure the past positive perspective (e.g. ‘Happy memories of good times spring readily to mind’). Ten items measure the past negative perspective (e.g. ‘Painful past experiences keep being replayed in my mind’). Fifteen items measure the present hedonistic perspective (e.g. ‘Taking risks keeps my life from becoming boring’). Nine items measure the present fatalistic perspective (e.g. ‘Since whatever will be will be, it doesn't really matter what I do’). Thirteen items measure the future perspective (‘Meeting tomorrow's deadlines and doing other necessary work comes before tonight's play’).

To create a short version of the ZTPI (SZTPI), we selected three items from each time perspective facet based on several criteria used in previous studies (Rammstedt and John, 2007; Saucier, 1994). First, we desired to maximize the breadth of coverage by selecting the three items that best represented each facet of the ZTPI while attempting not to be redundant in content. Second, we selected items that were not evaluatively extreme. Third, we examined each item’s corrected item-total correlation and factor loading from a simple-structure factor analysis. Fourth, we considered the content validity and readability of each item. The 15 items of the SZTPI-15 are shown in the Appendix.

To demonstrate convergent validity we correlated the SZTPI-15 with a battery of measures related to time perspective.

Big Five Mini Marker

Individuals in samples 2 and 3 completed Saucier’s (1994) 40-item mini-markers scale to measure the personality dimensions of the Five Factor Model of personality. Saucier’s mini-markers scale provides a list of 40 adjectives (eight for each personality dimension) and asks the participant to rate how accurately each trait describes him- or herself on a 9-point Likert-type scale (1 = extremely inaccurate, 9 = extremely accurate).

Big Five Inventory

To establish the validity of the SZTPI-15 with a different measure of the Five Factor Model of personality, participants in samples 4 and 5 completed the 44-item Big Five Inventory (BFI; John and Srivastava, 1999). When answering the 44-item Big Five Inventory, participants indicate how much they agree with specific phrases that describe personality characteristics on a five-point scale ranging from 1 (disagree strongly) to 5 (agree strongly). Examples of such phrases are as follows: for extraversion – ‘is outgoing, sociable’; agreeableness – ‘is generally trusting’; conscientiousness – ‘does a thorough job’; neuroticism – ‘gets nervous easily’ and openness – ‘has an active imagination’.

Life satisfaction

The Satisfaction with Life Scale (SWLS; Diener et al., 1985) assessed participants’ perceived satisfaction with life. An example item is ‘in most ways my life is close to my ideal.’ It is a five-item measure rated on a 7-point Likert-type scale ranging from 1 (strongly disagree) to 7 (strongly agree).

Positive and Negative Affect

The Positive and Negative Affect Schedule (PANAS) (Watson et al., 1988) contains a 10-item Positive Affect (PA) scale and a 10-item Negative Affect (NA) scale. Participants rate the extent to which they have felt specific positive (e.g. enthusiastic) and negative (e.g. nervous) emotions over the past few weeks (1 = very slightly; 5 = extremely).

Procedures

Participants from sample 1 (N = 726) completed the full ZTPI and SWLS. Participants in Sample 2 (N = 641) and 3 (N = 279) completed the ZTPI, Big Five Mini Marker, SWLS and PANAS. Participants in Sample 4 (N = 143) and 5 (N = 360) completed the ZTPI, BFI, SWLS and PANAS. Test–retest reliability was examined by requesting participants from Sample 6 (N = 76) to complete the ZTPI two times at four weeks apart. The same participants from sample 6 were asked to nominate two people who know them well and could serve as informants. These informants completed the same measures that the participants had completed. Both the informants and the participants were told that neither of their answers would be revealed.

Results

Convergent and discriminant validity

As with any attempt to reduce a long scale into a shorter measure, it is important to examine how well the short scale generalizes to the full scale. The convergent correlations in sample 1 between the short ZTPI-15 and full ZTPI are displayed diagonally in bold face in Table 1. The discriminant correlations for the short ZTPI are shown below the diagonal, and the discriminant correlations for the full ZTPI are shown above the diagonal (Gosling et al., 2003). For sample 1, the mean convergent correlation of 0.75 is much larger than the absolute mean of the off-diagonal discriminant correlation of 0.21. The convergent and discriminant (off-diagonal) correlations of samples 2, 3, 4 and 5 are summarized in Table 2. The patterns of convergent and off-diagonal discriminant correlations for samples 2, 3, 4 and 5 were similar to sample 1. Moreover, the convergent correlations were also much larger than the discriminant correlations in these samples. As shown in Table 1, we found strong correlations in all six samples and an overall mean correlation of 0.78; this correlation suggests that the SZTPI-15 predicts 61% of the variance of the full scale. All five time perspective showed very similar overall mean convergent correlations. In other words, the short scale was able to explain 53% for future to 69% for past negative of the variance in the full ZTPI.

Table 1.

Convergent correlations between Short ZTPI-15 and full ZTPI

Full ZTPI
Short ZTPI-15	PP	PN	PH	PF	F
1. Past Positive	0.73***	−0.35***	0.06	−0.01	0.23***
2. Past Negative	−0.04	0.81***	0.18***	0.36***	−0.08*
3. Present Hedonism	0.26***	0.16***	0.78***	0.31***	0.04
4. Present Fatalism	0.17***	0.33***	0.28***	0.75***	−0.11**
5. Future	0.16***	−0.06	−0.18***	−0.18***	0.67***

Note. N = 726. PP, Past Positive; PN, Past Negative; PH, Present Hedonism; PF, Present Fatalism; F, Future. Convergent correlations are shown in bold in diagonal. Discriminant correlations are shown below the diagonal for the Short ZTPI-15 and above the diagonal for the full ZTPI.

Table 2.

Summary of convergent, discriminant correlations, and self-peer convergent correlations across the ZTPI

	Samples					Self-peer convergent correlations
	1 (N = 726)	2 (N = 641)	3 (N = 279)	4 (N = 143)	5 (N = 360)	Mean	Short ZTPI	Full ZTPI
Convergent correlations with full ZTPI
Past Positive	0.73	0.73	0.82	0.85	0.82	0.79	0.35	0.44
Past Negative	0.81	0.84	0.82	0.87	0.83	0.83	0.41	0.52
Present Hedonism	0.78	0.80	0.83	0.80	0.78	0.80	0.39	0.53
Present Fatalism	0.75	0.82	0.77	0.83	0.72	0.78	0.36	0.34
Future	0.67	0.75	0.71	0.79	0.70	0.72	0.35	0.45
Mean	0.75	0.79	0.79	0.83	0.77	0.78	0.37	0.45
Discriminant correlations (absolute means)
Full ZTPI	0.24	0.21	0.19	0.21	0.23	0.22
Short ZTPI-15	0.17	0.19	0.14	0.17	0.13	0.16
Mean	0.21	0.20	0.17	0.19	0.18	0.19

Note. Discriminant correlations are the means of the absolute off-diagonal correlations. All means were computed using Fisher r-to-z transformations, and are shown in boldface type. Sample 6 (N = 76) was a convergent of self-peer rating.

Test–retest reliability

We obtained test–retest reliability by correlating scores from time 1 and time 2. As Table 3 shows, the test–retest reliability is adequate for the full and short ZTPI. The mean retest reliability for the standard ZTPI is 0.75 and the short ZTPI averaged 0.73. The stability variance of the ZTPI was 57%, whereas the stability variance of the short ZTPI was 53%. In other words, the short ZTPI was just as stable as the full ZTPI.

Table 3.

Test–retest reliability of the Short ZTPI-15 and full ZTPI

Test–retest reliability
Full ZTPI	Short ZTPI
Past Positive	0.73	Past Positive	0.70
Past Negative	0.85	Past Negative	0.80
Present Hedonism	0.76	Present Hedonism	0.74
Present Fatalism	0.66	Present Fatalism	0.64
Future	0.77	Future	0.75
Mean	0.75	Mean	0.73

Note. N = 67. Test–retest correlation was across a 4-week interval. Nine people were removed from analysis because the standard deviation of their scores was too small compared to a previous sample (Zimbardo and Boyd, 1999).

External correlates

Did the short ZTPI-15 and full ZTPI show similar patterns of correlates with other constructs? To answer this question, we correlated both versions with the Big Five Mini-marker, Big Five Inventory, Satisfaction with Life Scale, and positive and negative affect (see Table 4). Because of the large number of correlations, we computed row-vector correlations for each time perspective subscale. The transformed correlations (Fisher’s r-to-z formula) are compared between the long and short measure and across the same subscales (e.g. full past positive with short past positive). These row-vector correlations suggest that the patterns of correlations between the long and short ZTPI were nearly identical. As can be seen in Table 4, the row-vector correlations between each subscale ranged from 0.865 to 0.999 across four samples. While the patterns of correlations are similar between the long and short ZTPI, we would expect the short ZTPI to display weaker correlations because it is less reliable. Indeed, the mean absolute magnitude of the correlations for the short ZTPI was consistently weaker than the long ZTPI; however, these differences are small.

Table 4.

External correlates of the Short ZTPI-15 and full ZTPI

	Big Five Mini Marker					Big Five Inventory
	E	A	C	N	O	E	A	C	N	O	SWLS	PA	NA	Row-vector Correlations	Mean absolute magnitude correlation
Sample2
SPP	0.07	0.25***	0.09	0.05	0.18**	–	–	–	–	–	0.23***	0.20***	−0.03	0.865	0.14
PP	0.12**	0.24***	0.14**	0.14**	0.20***	–	–	–	–	–	0.34***	0.17***	−0.16***	0.18
SPN	−0.23***	−0.13**	−0.18***	−0.43***	−0.05	–	–	–	–	–	−0.33***	−0.09	0.32***	0.998	0.22
PN	−0.30***	−0.14**	−0.26***	−0.52***	−0.06	–	–	–	–	–	−0.42***	−0.10*	0.38***	0.27
SPH	0.20***	0.07	−0.18***	−0.06	0.19***	–	–	–	–	–	0.11*	0.06	−0.01	0.975	0.11
PH	0.18***	0.13**	−0.19***	−0.09	0.23***	–	–	–	–	–	0.14**	0.11*	0.02	0.13
SPF	−0.26***	−0.31***	−0.32***	−0.27***	−0.24***	–	–	–	–	–	−0.22***	−0.14*	0.23***	0.981	0.24
PF	−0.22***	−0.23***	−0.35***	−0.29***	−0.20***	–	–	–	–	–	−0.24***	−0.12*	0.28***	0.24
SF	0.15**	0.28***	0.45***	0.14**	0.21***	–	–	–	–	–	0.20***	0.29***	−0.14**	0.952	0.23
F	0.08	0.27***	0.48***	0.02	0.19***	–	–	–	–	–	0.11*	0.21***	−0.12*	0.19
Sample3
SPP	0.20**	0.22**	0.17*	0.09	0.05	–	–	–	–	–	0.40***	0.18*	−0.04	0.967	0.17
PP	0.23**	0.27***	0.25**	0.16*	0.12	–	–	–	–	–	0.52***	0.30***	−0.13	0.24
SPN	−0.32***	−0.13	−0.24**	−0.36***	0.05	–	–	–	–	–	−0.45***	−0.16*	0.50***	0.999	0.27
PN	−0.37***	−0.14	−0.27***	−0.45***	0.04	–	–	–	–	–	−0.50***	−0.19**	0.56***	0.31
SPH	0.28***	−0.01	−0.03	−0.09	0.19*	–	–	–	–	–	0.18*	0.24**	−0.01	0.936	0.13
PH	0.28***	0.03	−0.09	−0.09	0.22**	–	–	–	–	–	0.16*	0.27***	0.11	0.15
SPF	−0.18*	−0.35***	−0.25**	−0.22**	−0.22**	–	–	–	–	–	−0.22**	−0.13	0.36***	0.982	0.24
PF	−0.18*	−0.26***	−0.22**	−0.20**	−0.21**	–	–	–	–	–	−0.16*	−0.03	0.34***	0.20
SF	0.17*	0.21**	0.48***	0.27***	0.14	–	–	–	–	–	0.25***	0.35***	−0.19**	0.891	0.25
F	0.16*	0.26***	0.46***	0.12	0.11	–	–	–	–	–	0.20**	0.28***	−0.02	0.20
Sample4
SPP	–	–	–	–	–	0.12	0.13	0.02	−0.02	−0.03	0.24**	0.21*	−0.04	0.910	0.10
PP	–	–	–	–	–	0.18*	0.17*	0.17*	−0.18*	−0.04	0.39***	0.27**	−0.17*	0.19
SPN	–	–	–	–	–	−0.13	−0.18*	−0.27**	0.42***	0.05	−0.33***	−0.15	0.36***	0.995	0.24
PN	–	–	–	–	–	−0.17*	−0.16	−0.34***	0.48***	0.09	−0.45***	−0.19*	0.46***	0.29
SPH	–	–	–	–	–	0.24**	0.04	−0.11	0.07	0.36***	−0.06	0.24**	0.06	0.908	0.15
PH	–	–	–	–	–	0.19*	0.12	−0.14	0.09	0.46***	0.10	0.24**	0.06	0.18
SPF	–	–	–	–	–	−0.30**	−0.08	−0.21**	0.23**	0.04	−0.12	−0.14	0.23**	0.984	0.16
PF	–	–	–	–	–	−0.23**	−0.07	−0.24**	0.24**	0.08	−0.10	−0.08	0.21*	0.15
SF	–	–	–	–	–	0.20*	0.20*	0.47***	−0.04	0.09	0.15	0.31***	−0.13	0.925	0.19
F	–	–	–	–	–	0.10	0.09	0.57***	0.01	0.02	0.19*	0.32***	−0.08	0.17
Sample5
SPP	–	–	–	–	–	0.28***	0.24***	0.12	−0.24***	0.04	0.39***	0.32***	−0.29***	0.989	0.24
PP	–	–	–	–	–	0.28***	0.29***	0.16**	−0.28***	0.10	0.43***	0.28***	−0.37***	0.27
SPN	–	–	–	–	–	−0.18**	−0.29***	−0.16**	0.39***	0.11	−0.43***	−0.16**	0.43***	0.988	0.26
PN	–	–	–	–	–	−0.12	−0.23***	−0.24***	0.38***	0.14*	−0.45***	−0.20**	0.43***	0.27
SPH	–	–	–	–	–	0.39***	0.02	−0.15*	−0.14*	0.32***	0.13*	0.29***	−0.04	0.973	0.19
PH	–	–	–	–	–	0.39***	0.10	−0.16**	−0.08	0.37***	0.10	0.23***	−0.06	0.19
SPF	–	–	–	–	–	−0.16**	−0.25**	−0.27***	0.08	−0.10	−0.17**	−0.24***	0.32***	0.900	0.19
PF	–	–	–	–	–	−0.05	−0.15*	−0.22***	0.09	−0.02	−0.15*	−0.23***	0.29***	0.15
SF	–	–	–	–	–	0.07	0.15*	0.63***	−0.17**	−0.13*	0.24***	0.32***	−0.18**	0.936	0.24
F	–	–	–	–	–	0.05	0.13*	0.55***	−0.04	0.04	0.09	0.21**	−0.17**	0.16

Note. SPP, Short Past Positive; SPN, Short Past Negative, SPH, Short Present Hedonism, SPF, Short Present Fatalism, SF, Short Future are facets from the Short ZTPI-15. PP, Past Positive; PN, Past Negative, PH, Present Hedonism, PF, Present Fatalism, F, Future are facets from the Full ZTPI. E = Extraversion; A = Agreeableness; C = Conscientiousness; N = Neuroticism; O = Openness. SWLS = Satisfaction with life. PA = Positive Affect and NA = Negative Affect. We did not include sample 1 because we only have data on Satisfaction with life. ‘—’ indicates that data were not available. * p < 0.05; ** p < 0.01; *** p < 0.001.

External validation: Correlations with peer ratings

We used informant reports as an alternative method for establishing construct validity (Rammstedt and John, 2007). We used informant reports because others’ evaluations are less likely to be influenced by social desirability and other biases (Vazire, 2006). However, because time perspective are internal traits that could be difficult for observers to assess (Vazire, 2010), we did not expect the magnitude of these correlations to be very strong or the mean differences to be large. Overall, the magnitude of the correlations was stronger for the full ZTPI (0.45) than the short ZTPI (0.37); again, however, this difference was rather small. Thus, the strength of the relationship between self-reports and informant-reports for the short ZTPI is similar to that for these relations for the long ZTPI and provides additional construct validity.

Discussion

In general, the short ZTPI is psychometrically sound and is a good proxy for the full ZTPI. The range of the test–retest scores for the standard (0.66–0.85) and short ZTPI (0.64–0.80) is very similar to the 0.70–0.80 range reported by Zimbardo and Boyd (1999). The 61% variance explained by the short ZTPI in the long ZTPI is comparable to the 68% reported by Gosling et al. (2003) and Rammstedt and John (60%; 2007) for shorter forms of Big Five personality measures. Also, external validity of the short ZTPI was supported by the nearly identical pattern of correlations observed between both the short and full ZTPI and personality traits and well-being. We further demonstrated construct validity using informant reports collected from knowledgeable informants.

Implications

The most important contribution this article offers is the development and validation of a short ZTPI. However, some interesting correlations also deserve attention. Similar to previous studies, past positive and past negative time perspectives demonstrated strong correlation with life satisfaction (Boniwell et al., 2010; Zhang and Howell, 2011). Thus, converging evidence is suggesting that being warm and having a sentimental attitude towards the past is a good predictor of increased life satisfaction. Past negative, on the other hand, reflects a generally painful and unpleasant view of the past and is associated with lower life satisfaction. The consistent relationship between past positive and increased life satisfaction is even more impressive given that a positive future time perspective is often touted as the time perspective that is most conducive to well-being (Wills et al., 2001; Zaleski et al., 2001). In the previous studies and in this study, however, the future time perspective did not show a strong correlation with life satisfaction. Zimbardo and Boyd (2008) noted that being too future-oriented can be detrimental to well-being. This may be because excessive future orientation may undermine some of the benefits associated with present hedonism, such as increased social companionship and more support from friends and acquaintances (Holman and Zimbardo, 2009). There is a need for further research to clarify the causal relationships between time perspective, well-being, and other variables. Such research may be facilitated with the availability of a validated short form of the ZPTI.

The current article also extended the short form of the Stanford Zimbardo Time Perspective Inventory (D’Alessio et al., 2003) and differed in a two aspects. For instance, while D’Alessio et al. based their validation effort on the Stanford version of the ZTPI (Zimbardo et al., 1997), we guided our validation procedures on the updated version of the ZTPI (Zimbardo and Boyd, 1999). Thus, our short form included the two past dimensions. This is important, because past research has shown that the two past dimensions correlate with personality traits and have important predictive implications for subjective well-being (Zhang and Howell, 2011; Zhang et al., 2012, forthcoming). Furthermore, the inclusion of all five dimensions enables researchers to compute a balanced time perspective score (Boniwell et al., 2010; Stolarski et al., 2011). In sum, the current short form stands as the most comprehensive validation of a short ZTPI.

On another note, the fact that we used informant reports further adds to our confidence in concluding that the short ZTPI is a valid measure of the ZTPI. The informant report is a powerful complement to the self-report method because the self-report provides an inner view of personality and the informant report reveals what others see in us (Hogan, 1998). The strong self–other agreement that we found is similar to what Gosling and his colleague discovered and is a strong indicator of the validity of the short ZTPI. Collecting informant reports reflects an effort towards achieving a multimethod study of subjective time. While researchers have called for the use of informant reports (see Vazire, 2006 for review), the study of time perspective is relatively weak in this respect. Future research should consider the use of informant reports as complementary to self-reports, because it is a more reliable assessment of a person’s personality.

Rigorous testing across multiple samples suggests that the short ZTPI possesses acceptable psychometric properties. Some obvious limitations, however, need to be pointed out. For one, the short scale is not quite as strongly correlated with related measures in comparison to the standard measure.

Conclusion

In the words of Burisch, ‘if very short and simple questionnaire scales do the same job, why use long and elaborate ones?’ (1984, p. 82). Also, if the long form of a scale is the only available measure of a construct that is widely used, like the ZTPI, then researchers may drop the measure or try to develop one ad hoc with less than adequate psychometric properties (Richins, 2004). Although the short ZTIP-15 is a bit less internally consistent and stable, it is psychometrically sound. Therefore, this brief ZTPI can be instrumental to future studies on subjective time when researchers are resource-constrained.

Footnotes

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