Subjective Time Perceptions and Aging Well: A Review of Concepts and Empirical Research - A Mini-Review

The passing of time is a self-evident fact, usually not thought much about as everyday life proceeds. However, if brought to awareness, the monitoring of self in time becomes a substantial part of individuals' self-knowledge [1]. Temporal comparisons with past selves or contemplating on the amount of time left to accomplish a goal are only 2 exemplary ways in which time perceptions influence behavior and decision making across the lifespan. In this review, we examine concepts and findings related to the fundamental human ability to ‘travel in time' and to interpret the temporal dimensions of one's life while aging [2].

Given the imperative need to conceptualize human development in relation to time, the utility of different “objective” time metrics (e.g., chronological age, distance- to-death) has become a major topic of gerontological research today [e.g., [3]]. In addition, frequently used self- report measures are anchored in diachronic thinking and may differ fundamentally depending on the time frame used (i.e., past, present, or future time framings). For example, self-rated future health is an independent predictor of mortality vis-à-vis the conventional self-rated present health [4]. Overall, subjective conceptions of personal lifetime and aging are on the rise in behavioral science and in aging research at large and have proven useful for the prediction of developmental outcomes over and above chronological age [5,6,7,8,9]. Theoretical and conceptual developments in this area (to be reviewed below) seem to remain loosely connected, if not disconnected, so far.

Therefore, we propose a conceptual organization of concepts and theoretical approaches related to subjective time in this mini-review. This conceptual model builds the basis for a synthesis of empirical research findings with a focus on implications for aging well. For reasons of space, we restrict our analysis to key outcomes, i.e. health and well-being. The review ends with a discussion of the usefulness of subjective time within lifespan developmental theories and a set of emerging propositions with importance for a future research agenda on subjective time and aging.

Our selection of concepts included in this review was based on our understanding of subjective time as the way individuals subjectively perceive and evaluate the passing of their personal “objective” lifetime and the meaning they ascribe to it. Hence, subjective time covers an individual's subjective perception of the duration, expansion, content, and valence of his/her individual lifespan from birth to death.

Concepts related to subjective time comprise diverse phenomena, for example future time perspective, personal goals, autobiographical memories. In our conceptual model of subjective time, we propose that constructs related to subjective time can be classified into a 3 × 3-field matrix consisting of the 2 dimensions temporal direction and thematic field (cf. Fig. 1).

Temporal direction refers to the notion of a “triadic time orientation.” It posits that subjective time is made up of a personal past, present, and future - a view that has been advocated both by philosophers and lifespan psychologists [5,10], and is reflected in neurocognitive capacities such as autonoetic consciousness [2].

Thematic field distinguishes the following 3 aspects: (1) duration or progression of one's personal lifetime and subjective expansion of one's future; (2) time-ordered life content, which comprises the life events and experiences related to past lifetime as well as possible contents of future life; and (3) time-related evaluations, attitudes, and mindsets applied to the passing of personal lifetime, which relates primarily to evaluative judgments of past experiences and future expectations and extends to evaluative cognitive-behavioral schemes. To illustrate the distinctions and interdependencies between the 3 aspects of thematic field, we take the example case of a 65-year-old man, who just transitioned into retirement. In terms of duration/expansion, the 40 years of his past working life might appear endless to this individual, while the 20 years he may still expect to live after retirement might feel like a very short amount of time left in life. With regard to time-ordered life content, looking back to his working life he might first think of countless hours spent at work without seeing his children grow up, therefore having the goal to spend as much time as possible with his grandchildren in the years to come. In terms of time-related evaluations, attitudes, and mindsets, this individual might have a tendency to dwell on missed opportunities, while at the same time remaining optimistic to achieve the goals set for the future.

Adding to Figure 1, Table 1 takes up the 3 thematic fields as well as respective subthemes and qualifies them in several ways. First, each subtheme including its connection with subjective time is defined. Second, we examine which function(s) these subjective time concepts fulfill as a motivational factor for developmental regulation. Third, we address reasonable assumptions how manifestations of each construct (and eventually its motivational functions) change across the adult lifespan.

Concepts related to the subjective duration/progression of time, although fundamental to human existence and development, have received little attention in theories of lifespan development. However, assumptions about its motivational consequences may be derived from socioemotional selectivity theory [SST; [7]]. SST is likely the most influential theory related to subjective time and human development and examines how the perceived expansion of remaining future lifetime¹ influences motivational processes. A central assumption is that with future time expansion becoming more limited in old age, people shift from a focus on future-oriented goals to prioritizing present-oriented goals, such as deriving emotional meaning and satisfaction. Given this increased focus on emotional states, perceiving one's future as limited should motivate endeavors to improve subjective well-being. Similarly to future time expansion, the subjective duration/progression of(past and present) time may have implications for the assessment of a given amount of time as being (in)sufficient for goal achievement. Therefore, an accelerated time perception may likewise trigger the perception of lifetime constraints and might motivate social-emotional goal pursuit.

Temporal self-regulation theory [[11]] establishes future time expansion as a predictor of health behavior. It holds that future time expansion influences the intention to engage in health protective behaviors with long-term benefits, because future time expansion provides an estimate about the likelihood of profiting from health behaviors. Hence, an open future time expansion is expected to be associated with improved physical health through health behavior.

The 2 concepts of remembering the personal past and awareness of one's personal future play a key role in lifespan development in terms of maintaining self-continuity [12] and in terms of motivating present behavior and goal pursuit [13]. Subjective time perceptions in terms of time-ordered life content are considered within motivational theories of lifespan development, such as lifespan theory of control [14] or the 2-process model of goal-pursuit and goal adjustment [15]. The theories claim that working towards the accomplishment of one's future plans by exerting primary control is necessary for realizing one's developmental potential. At the same time, the adaptive functions of primary control diminish with decreasing action resources (such as time left to live) in later life. Therefore, with increasing age, flexible goal adjustment and retrospective reflection of one's life may fulfill increasingly important functions of coping with life discrepancies by creating a sense of coherence and maintaining high levels of well-being in later life.

The third dimension of our classification scheme focuses on the valence that dominates the recall or anticipation of life events. Respective concepts that appear in the literature can be categorized into cognitive mindsets toward past experiences (e.g., rumination, regret) and mindsets toward future expectations (e.g., optimism, worry). Furthermore, attitudes toward aging² comprise past-present evaluations with reference to age norms and age stereotypes. A concept that attends to emotional valence and behavioral tendencies related to past, present, and future and has the potential to integrate the 3 temporal directions has been introduced by Zimbardo and Boyd [16] with their conceptual model of “time perspective.” Zimbardo and Boyd identified 5 evaluative time orientations, i.e. past-positive, past-negative, present-hedonistic, present-fatalistic, and future.

Constructs classified in the dimension of time-related evaluations, attitudes, and mindsets go beyond the perception of time as time-ordered life content in that they involve an explicit evaluation of past and future life content. In her theoretical work on “life reflection,” Staudinger [17] proposed that it is exactly such further evaluation and (re-) constructive analysis (as opposed to simply remembering autobiographical events) that is associated with adjustment in later life. With regard to representations of the future, it appears that negatively and positively valenced thoughts fulfill distinctive motivational functions. While optimistic scenarios about the future stimulate goal-directed behavior [18], negative or pessimistic future expectations may motivate preventive behavior and anticipatory coping - particularly in old age when developmental losses become a more realistic representation of the future [e.g., [19]].

Our proposal for a conceptual model of subjective time aims at an overall picture which is up for scientific debate. For one, we acknowledge that in certain cases the 3 thematic fields can be differentiated only at the analytical level. Consequently, the assignment of certain constructs to the 3 thematic fields is not definite, as some concepts cover aspects of multiple thematic fields (e.g., future time perspective, attitudes toward aging). Second, it remains an open question if the 3 proposed thematic fields exist in parallel or involve some kind of hierarchical ordering. For example, a restricted view of the future might trigger an awareness of fewer life events to be expected for the personal future which in turn might lead to more pessimistic mindsets toward future expectations. Third, at first glance Figure 1 might suggest that subjective time perceptions are dominated by past- and future-oriented time frames, while present-moment experiences play only a limited role. The only distinct present-oriented construct seems to be a present-hedonistic time orientation (as part of “emotional valence and behavioral tendencies related to past, present, and future”). Such a gap regarding duration/expansion and time-ordered content of subjective time perceptions might be owed to fleetingness of the present moment, which is therefore inaccessible for an extensive reflection of contents. However, as depicted through the white boxes reaching from the past or future into the present moment, the presence is the timeframe in which perceptions of the past and future are being realized (e.g., through past-present comparisons) and thus represents the link between past and future.

Our review of the empirical literature is organized along the 3 thematic fields of our conceptual model (see again Fig. 1 and Table 1). We focused on key indicators of successful aging, namely subjective well-being and physical health, which were operationalized by several constructs (subjective well-being: life satisfaction, positive and negative affect, and depressive symptoms; physical health: objective and subjective health, physical functioning, and mortality). We included key studies which were published since the year 2000 and employed the following selection criteria: (1) assessment of at least 1 subjective time construct with a well-established instrument³, (2) inclusion of at least 1 outcome measure of subjective well-being or physical health, (3) middle-aged and/or older adult sample drawn from a nonclinical population. Our selection was also guided by methodological aspects, i.e. size and representativeness of the study sample, in order to ensure high quality of the reported findings. Finally, we prioritized studies with a longitudinal or meta-analytical character where possible.

An upcoming body of research applies ecological momentary assessment methods to the perceived duration/progression of time, acknowledging its continuous monitoring in everyday life and references to the present moment.John and Lang [20] examined the effects of accelerated time perceptions on well-being in an adult lifespan sample. Individuals who experienced time to be passing more quickly in everyday life reported better mood than individuals with a slower subjective progression of time. Given the cross-sectional design, the direction of effects as well as underlying mechanisms remain unclear.

With regard to expansion of future time, studies have accumulated showing that an expanded future time perspective is associated with higher levels of well-being as indicated by higher positive affect and life satisfaction as well as less negative affect and fewer depressive symptoms [21,22,23]. Likewise, an expanded future time perspective was found to be linked to a reduced risk of mortality 6.5 years later [24]. The effect may be mediated by health behaviors such as physical activity [25].

While SST [7] posits that a limited future time expansion motivates a higher focus on social-emotional goals, empirical evidence indicates that such a heightened focus on social-emotional goals may not necessarily translate into higher levels of well-being: An extended (not a limited) future time expansion was associated with higher levels of well-being. Thus, although individuals with a limited future time expansion optimize social-emotional goals, it might be necessary for them to also preserve openness for new information and opportunities in order to maintain well-being. With regard to health, the empirical findings support temporal self-regulation theory, which postulates that an expanded view of the future leads to better health through preventive health behaviors [11].

O'Rourke et al. [26] found that the association between remembering the personal past and well-being depends on reminiscence functions. They found that self-positive modes (e.g., problem-solving) of reminiscence lead to higher well-being 16 months later, while self-negative modes (e.g., boredom reduction) were associated with lower well-being and also exerted a larger effect.

Goals, as a central part of awareness of one's personal future, become increasingly important in old age when resources start to decline. The experience of goal failure can elicit emotional distress and health problems. Wrosch [27] argued that individuals can avoid these negative consequences if they disengage from unattainable goals and engage in new meaningful goals. A number of studies showed that goal disengagement capacities reduce negative emotions and thereby contribute to physical health. Goal re-engagement capacities, by contrast, did not predict health-related outcomes but were positively associated with psychological well-being [27].

Besides goals, less binding expectations about the future have been found to predict developmental outcomes. Positive future health expectations (rather than retrospectively recalled health changes) were associated with a lower risk of mortality over a 10-year period [4]. Desire to live or adaptive health behaviors have been proposed as mediating pathways in this association. In addition, it seems important to consider the fit between retrospective, present, and prospective/anticipated ratings of the self. Individuals who underestimated their future selves had higher levels of well-being 12 months later than those who overestimated their future selves [28]. Comparable results were obtained by Lang et al. [29]. In later adulthood, underestimating one's life satisfaction over a 5-year interval was associated with lower hazard ratios for disability or mortality 10 years later. The authors concluded that foreseeing a bad future immunizes the self against possible threats and enhances early (behavioral) interventions which maintain well-being in the long run.

As discussed above, looking ahead, planning, and pursuing goals are important strategies in the first half of the lifespan to ensure growth and development. In line with theoretical assumptions [14,15], empirical findings show that the loss of resources in old age requires adjustment of goals [27]. Ideally, an awareness of potential future losses may function as a trigger of proactive coping efforts [29]. At the same time, the proactive confrontation with one's life story in terms of reminiscence contributes to creating a sense of coherence and consistency, thereby fostering high levels of well-being [26].

Most studies about mindsets toward past experiences focus on negative thoughts, such as rumination, which was associated with depressed mood both cross-sectionally and longitudinally [30]. The authors concluded that ruminative reminiscing keeps exposing individuals to negative thoughts and memories, thereby reinforcing the negative emotions attached to them. Worry, a negatively valenced mindset toward future expectations, is likewise associated with worsened subjective well-being and physical health [31]. The association with health was amplified by the number of repetitive thoughts. Focusing on positive mindsets toward future expectations, Stern et al. [32] asked participants whether they were hopeful about their future. Hopeless individuals had a significantly higher likelihood of having died 5.2 years later than hopeful participants. Going further, increases in optimism over a 4-year period were associated with better self-rated health and fewer chronic illnesses [33]. Wurm and Benyamini [34] showed that dispositional optimism may also buffer the hazardous effects of negative attitudes toward aging that have otherwise been shown as a risk factor for physical health [35].

Studying emotional valence and behavioral tendencies related to past, present, and future, Desmyter and De Raedt [36] found that future-oriented persons (who focus on future rewards) had more positive affect. Persons with a positive orientation towards the past reported a higher life satisfaction, whereas persons with a negative outlook on the past were more likely to report negative affect and depressive feelings. A hedonistic view of the present was associated with more positive affect, whereas a fatalistic view of the present was linked to more depressive symptoms.

In general, and in line with theoretical considerations, positively valenced time-related evaluations, attitudes, and mindsets are associated with enhanced well-being and better physical health, while negatively valenced time-related evaluations, attitudes, and mindsets lead to lower levels of health and well-being.

In this mini-review, we developed a conceptual model of subjective time according to 2 dimensions: temporal direction (past, present, future) and thematic field (“duration/expansion,” “time-ordered life content,” and “time-related evaluations, attitudes, and mindsets”). To conclude, we first summarize key insights that emerge from the review of empirical associations of subjective time with major endpoints of successful aging. We then delineate avenues for future research and theory building.

Subjective time concepts emerged as a consistent predictor of health and well-being in middle-age and late adulthood. With regard to “duration/expansion” of subjective time, it is interesting that despite the motivational shift toward emotion-oriented goals posited by SST, studies examining relations between future time expansion and well-being have emerged only recently in the empirical literature. This body of findings suggests that a more restricted view of the future is linked to lower well-being [22]. Understanding the underlying mechanisms of this association (e.g., resource limitations that may impede emotional goal achievement or failure to preserve an openness for new opportunities) requires further empirical research. Likewise, lifespan dynamics regarding the “subjective duration/progression of time” demand more research efforts as well as theoretical deliberation in the future. In general, it seems that a positively valenced subjective time perception is associated with higher well-being and better physical health, while negative subjective time perceptions in general were linked to lower levels of health and well-being. This consistent pattern of associations was found within the thematic fields of “time-ordered life content” and “time-related evaluations, attitudes, and mindsets.” At the same time, a constructive and proactive confrontation of negative future life contents seems to become more important for adjustment with increasing age. For example, some studies suggest that foreseeing a worse future may turn out as beneficial for preserving well-being, potentially because of anticipatory coping efforts triggered by negative future expectations [28,29]. The conditions under which negatively valenced thoughts about the future contribute to adjustment in later life still request further scientific research.

Contrasting past and future orientations, it seems that past-oriented time perceptions have been studied primarily in connection with well-being (with attitudes toward aging being one important exception in this regard). In contrast, empirical links with both health and well-being have been established for future-oriented time perceptions [4]. Mechanisms that link both past- and future-oriented subjective time perceptions with developmental outcomes require further empirical investigation. An important pathway in the association between future orientations and health seems to go through behavioral efforts to achieve or avoid a future goal [25].

From a more theoretical perspective, we believe that there is heuristic value in our attempt to set existing constructs of subjective time into context. First, the literature on conceptual approaches to subjective time and respective empirical research is scattered, and our scheme may help to better link conceptually related research traditions. To this end, the simultaneous consideration of different subjective time concepts is necessary to gain a more comprehensive understanding of conceptual distinctions between constructs and about the ways in which temporal direction and thematic aspects of subjective time influence health and well-being in later life. Moreover, studying the interplay between different conceptual approaches would help to widen our understanding of the mechanisms and conditions that link subjective time to developmental outcomes. For example, although SST (classified within the thematic field of duration/expansion) has been highly productive in its conceptual impetus and empirical translation, new developments may arise if future time expansion is considered together with other subjective time approaches that may function as antecedents [e.g., attitudes toward aging, as in [22]], or as outcomes and mediators of future time expansion (e.g., mindsets towards future expectations). We believe that such a focus on interlinkages across the borders of thematic fields and temporal directions will lead to a more complex understanding of subjective time and its role in human development as compared to picking out single subjective time constructs.

Second, our conceptual model leads to the question whether there is some kind of hierarchical organization built into the cognitive processing of subjective time. For example, one may speculate whether there is a cascade-like process of perceiving limitations to the duration of personal lifetime, which drives a focus on specific time-ordered life contents, which in turn fosters certain time-related evaluations, attitudes, and mindsets. Obviously, such complex issues need more conceptual refinement in the future and may infuse a psychological theory of subjective time to come. In this regard, theory building might benefit from well-established theoretical models that are centered around certain subjective time concepts, such as SST [7] or developmental regulation approaches [27]. Other families of subjective time constructs, such as attitudes toward aging, however, have been extensively investigated and proven as a useful predictor of developmental outcomes [35], although the theoretical underpinning of underlying mechanisms is still scarce [9]. An emerging theory of subjective time will need to close these gaps in the future.

Third, it is striking that despite the broad age range covered by the reviewed empirical studies, the focus has rarely been on the oldest-old subpopulation. When aiming at the development of a theory of subjective time that takes into account the entire adult lifespan, it may be of particular importance to learn about subjective time and its psychological role when time is running out and the human system reaches its highest level of vulnerability. To this end, we also lack longitudinal data able to allow the complex modelling of subjective time (ideally a set of subjective time constructs) across longer time intervals.

In closing, we arrive at 3 propositions that may bring new impulses to research on subjective time and psychological aging research at large: (1) conceptually, we believe that a stronger integration of subjective time constructs into developmental regulation models deepens the understanding of human development across the lifespan; (2) both at the theoretical and the empirical level, we make a plea for interlinking different research traditions related to time perception, be it by integrating different subjective time concepts into 1 model [e.g., [22]], or by linking subjective time constructs with objective time metrics, such as distance to death [e.g., [37]]; (3) empirically, there is a need to extend methodological procedures (i.e., longitudinal research designs as well as a focus on the oldest-old) to gather profound findings about the role of subjective time constructs over the entire adult lifespan and to inform a “lifespan theory of subjective time.” Overall, we anticipate that taking subjective time seriously will contribute to the conceptual and empirical evidence questioning the role of calendar age, which often still enjoys a too prominent role as a predictor in lifespan developmental research.

A.J. Dutt was supported by a scholarship from the Konrad-Adenauer-Stiftung.