Introduction

Anhedonia is one of the negative symptoms of schizophrenia and is also a key feature of depression associated with social functioning in these patients [1], [2]. Anhedonia refers to the loss or a reduction of the ability to experience pleasure [3]. In addition, similar emotional and personality disturbances have also been demonstrated in individuals at-risk for psychosis (c.f. [4]) and sub-clinical individuals with depressive symptoms (e.g., [5]). Klein [3] argues that anticipatory pleasure involves a feeling of wanting and is associated with motivation and goal-directed behavior, whereas consummatory pleasure involves a feeling of liking and is associated with satiation, or a resolution/fulfilling of a desire. Empirical evidence from social cognitive neuroscience and affective science also supports the distinction between consummatory pleasure and anticipatory pleasure [6]–[12].

However, most of the measures of anhedonia are limited to clinical rating scales and self-report trait questionnaires that adopt a unitary concept, particularly the in-the-moment experience of pleasure or consummatory pleasure (c.f. [4]). Anticipatory pleasure has not been as thoroughly studied. Despite the fact that many studies employ questionnaire based methods to assess trait positive emotion (e.g., [13]–[15]) and in-the-moment experience, very few scales or questionnaires have been designed to capture both anticipatory and consummatory constructs of pleasure.

Gard et al. [16] developed the Temporal Experience of Pleasure Scale (TEPS) to specifically capture these two distinct constructs of anticipatory and consummatory pleasure. It is a short questionnaire with 18 self-reported items (10 items for anticipatory pleasure, 8 for consummatory pleasure) allowing for easy administration. Examination of the scale factor structure in North American samples showed that the TEPS comprised the hypothesized 2-factor model for anticipatory and consummatory pleasure among 4 independent samples of university students [16]. Gard et al. [17] also demonstrated that patients with schizophrenia anticipated less pleasure from future activities than healthy controls during the course of daily life, and thereby, provided further evidence for the deficit of anticipatory pleasure in schizophrenia.

However, all the aforementioned findings were derived from Western samples. Given the potential for cultural differences of emotional experience between Western and Eastern people, the two factors in the TEPS may not fully capture cultural influences. For example, Chinese culture emphasizes the internal and external harmonious conditions between self and external environment as well as body and mind, i.e., the concept of Yi-Yang and Taoism [18]. Individuals are obligated to maintain their own internal harmonious condition through adjusting themselves to “context”. According to this belief, harmony is more or less equivalent to pleasure. Chinese people report lower frequency and intensity of emotional experience as compared to their Western counterparts [19]–[21]. One pilot study using the Chinese version of TEPS [22] showed impressive clinical utility of this scale in differentiating patients with schizophrenia characterized by negative symptoms from those patients without negative symptoms. However, the psychometric properties of the Chinese version of TEPS have not been fully examined.

The current study aimed to examine the factor structure of the TEPS in a large Chinese sample of healthy people. Given the cultural differences between the East and the West, we hypothesized that Chinese people would take less account of the difference in context between present and future time points when they prospect the future, as opposed to their Western counterparts. The secondary aim was to evaluate the internal consistency and test-retest reliability of the translated TEPS at a 4-week interval

Methods

Results

EPA and CFA

Item-total correlation analyses were performed on the 20 items of the Chinese version of TEPS in sample A of 1156 participants. Item 13, “I don't look forward to things like eating out at restaurants. (Anticipatory)”, had no or very low correlations with other items and was discarded in further analyses (Tables 1 and 2). Examination of the scree plot indicated a four-factor solution. Consistent with the two-factor model proposed by Gard et al [16], two of the four factors belonged to the Consummatory factor and the other two belonged to the Anticipatory factor. The two new items (19 and 20) loaded on the consummatory and anticipatory factors respectively as hypothesized.

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Table 1. Correlation matrix of the 20 items of the Chinese translated version of TEPS in the 1156 calibration sample of Chinese participants.

https://doi.org/10.1371/journal.pone.0035352.t001

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Table 2. Factor loadings of the 4-factor solution for the translated 19-item TEPS in the calibration sample.

https://doi.org/10.1371/journal.pone.0035352.t002

Examination of the meaning in the items of the four factors revealed additional dimensions of the TEPS in Chinese, and the dimensions were named abstract and contextual. Therefore, the four factors of the Chinese version of TEPS were: Abstract Anticipatory (anticipation of something that is more abstract or broad in nature such as “I look forward to a lot of things in my life.”), Contextual Anticipatory (anticipation of something that is more concrete in nature such as “When I think of something tasty, like a chocolate chip cookie, I have to have one.”), Abstract Consummatory (consummation of emotional experience of something that is more abstract or less concrete in nature such as “I enjoy taking a deep breath of fresh air when I walk outside.”) and Contextual Consummatory (consummatory of emotional experience of more concrete in nature such as “When I think about eating my favorite food, I can almost taste how good it is.”). It was noteworthy that items 5 and 19 had low factor loadings on the Contextual Anticipatory factor (factor loading = 0.36) and the Abstract Consummatory factor (factor loading = 0.28), respectively. In addition, item 19 tended to have a cross factor loading on the Contextual Consummatory factors. In order to address this issue in the CFA analyses, we performed the CFA analyses with and without these two items. However, the overall fit for all studied models without these two items was not satisfactory. After consideration of the findings from both the EFA and CFA, we decided to retain these two items in the CFA analyses presented in the next paragraph.

In addition to the original Gard et al. [16] two-factor model and the current EFA four-factor model, a second-order four-factor model was also tested with CFA [32]. That is, the four factors of TEPS could be further factor analyzed into the original Anticipatory and Consummatory factors. All three models were tested using the SB approach with the validation sample of 1119 participants (sample B), and the four-factor model identified by the EFA yielded the best fit (Table 3). The more computationally intensive Bollen-Stine bootstrapping approach was performed only on the four-factor model. Means and 95% confidence intervals (CIs) for the fit indices and factor loadings (Figure 1 loadings plus mean+95% CI) were presented side by side with the estimates obtained by the SB approach. Estimates were within the 95% CIs unless the estimates were dependent on the sample size, which showed better results using the bootstrapping method. The two-stage factor analysis using EFA and CFA on two randomly drawn sub-samples, and the convergence of the CFA results using the SB method and the Bollen-Stine bootstrapping method provided strong empirical support for the four-factor structure of the Chinese version of TEPS.

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Figure 1. Four-factor model of the Chinese translated TEPS in the validation sample – Factor loadings and correlations between factors estimated by the Satorra-Bentler (SB) method, and their means (which is the same as the estimates by the SB method at 2 decimal places) and 95% confidence intervals (in brackets) estimated by the Bollen-Stine bootstrapping method.

https://doi.org/10.1371/journal.pone.0035352.g001

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Table 3. Evaluative measures of model fit by the three models, and the Bollen-Stine bootstrap estimates for the 4-factor model in the 1119 validation sample of Chinese participants.

https://doi.org/10.1371/journal.pone.0035352.t003

Discussion

Through testing two alternative models: the original two-factor model by Gard et al. [16] and a four-factor model, we found that the four-factor model, namely the anticipatory contextual, anticipatory abstract, consummatory contextual, and consummatory abstract, was a better fit to the current study's large Chinese sample. The current findings were broadly consistent with Western findings that subjective experience of pleasure can be classified into consummatory and anticipatory components [16], [17]. However, our findings further showed that both the consummatory and anticipatory factors could be further sub-divided into abstract and contextual factors in the Chinese context.

Because selecting information from memory to represent the future is highly relevant to an individual's goals, beliefs and concerns [33], it is possible that frequency of events will facilitate access to reaching them in memory. For the consummatory aspect of the TEPS, those contextual items refer to more physical feelings such as satiation to food, may occur more frequently during daily life than more abstract items. If these experiences are more readily recalled, they may be perceived as subjectively closer to the present by Chinese individuals. The focus on food and eating, an obviously common experience, may also help explain why two anticipatory items from the original TEPS fit on the Contextual Consummatory factor in the Chinese context.

Anecdotally, Chinese respondents took longer to rate the anticipatory abstract items of the TEPS which described very general events. Perhaps it was more difficult for them to envision a non-specific event since they relied on past experience to answer contextual items and were less able to do so for abstract items. However, since the previous studies in other countries did not take the account the response time to rate the anticipatory items, we do not know whether it is really more difficult for Chinese participants to envision a non-specific event than their Western counterparts.

It is important to note that the current findings are not directly comparable to the Western studies of the TEPS because there are differences in statistical approach and other methodological factors (e.g., nature of the study samples). Indeed, given the complexity of cultural differences, and the absence of any non-Chinese comparison group, the current study only provides preliminary evidence for cross-cultural aspects to the temporal experience of pleasure. Without comparable cross-cultural samples between Chinese and Westerner counterparts, we are not confident that the 4 factors generated from the current Chinese sample reflect true cultural differences. The current findings might be either due to cultural or language factors (along with sampling bias and measurement error). Further studies using more rigorous approaches and objective methods such as behavioral experiments [17] and brain imaging paradigms [34] are required to further validate these potential cross-cultural variations of the temporal experience of pleasure. Similarly, it is noteworthy that the labels of “abstract” versus “contextual” appear appropriate for the anticipatory items. However, this dichotomy does not seem to fit as well in distinguishing the two consummatory factors. That is, the items on the “abstract” consummatory factor may also refer to specific contextual pleasures. Indeed, the idea of a consummatory pleasure may be inherently contextual. Moreover, future studies should expand the healthy group size and include community samples in order to cross validate the current factors, particularly to distinguish the two consummatory factors, and to determine whether this Chinese version of TEPS, which includes one more directly social anticipatory item than the original TEPS, will maintain its usefulness in community settings.

In a preliminary study of the TEPS in Chinese patients with schizophrenia [22], we found that patients with minimal negative symptoms experienced significantly more pleasure in contextual anticipatory and contextual consummatory factors than negative symptom patients. Those patients with minimal negative symptoms also exhibited a tendency to experience more abstract anticipatory pleasure than negative symptom ones but there was no significant difference in abstract consummatory pleasure. TEPS scores were also inversely associated with clinical symptom levels [22]. However, since the patients we studied were a relatively chronic sample of patients, we do not know whether a similar deficit would be demonstrated in patients at the early stage of the illness. Therefore, studies are needed that include a wider range of patients at different stages of the illness and different clinical diagnoses (i.e., major depressive and bipolar disorders) with specific anhedonia symptoms in order to determine clinical discrimination across clinical diagnoses.

Taken together, the current study is the first one to examine the factor structure of the TEPS in a Chinese sample. The TEPS is specifically developed to capture two faces of trait hedonic capacity and has been demonstrated with impressive latent structure for researchers to study hedonic trait in healthy Chinese participants.