Representing time in language and memory: The role of similarity structure

Every day we read about or watch events in the world and can easily understand or remember how long they last. What aspects of an event are retained in memory? And how do we extract temporal information from our memory representations? These issues are central to human cognition, as they underlie a fundamental aspect of our mental life, namely our representation of time. This paper reviews previous language studies and reports a visual learning study indicating that properties of the events encoded in memory shape the representation of their duration. The evidence indicates that for a given event, the extent to which its associated properties or sub-components differ from one another modulates our representation of its duration. These properties include the similarity between sub-events and the similarity between the situational contexts in which an event occurs. We suggest that the diversity of representations that we associate with events in memory plays an important role in remembering and estimating the duration of experienced or described events.     

Binding actions and scenes in visual long-term memory

How does visual long-term memory store representations of different entities (e.g., objects, actions, and scenes) that are present in the same visual event? Are the different entities stored as an integrated representation in memory, or are they stored separately? To address this question, we asked observers to view a large number of events; in each event, an action was performed within a scene. Afterward, the participants were shown pairs of action–scene sets and indicated which of the two they had seen. When the task required recognizing the individual actions and scenes, performance was high (80 %). Conversely, when the task required remembering which actions had occurred within which scenes, performance was significantly lower (59 %). We observed this dissociation between memory for individual entities and memory for entity bindings across multiple testing conditions and presentation durations. These experiments indicate that visual long-term memory stores information about actions and information about scenes separately from one another, even when an action and scene were observed together in the same visual event. These findings also highlight an important limitation of human memory: Situations that require remembering actions and scenes as integrated events (e.g., eyewitness testimony) may be particularly vulnerable to memory errors.     

Effects of event structure on retrospective duration judgments

Two experiments examined whether varying degrees of event coherence influence the remembering of an event’s actual duration. Relying on musical compositions (Experiment 1) or filmed narratives (Experiment 2) as experimental stimuli, the underlying hierarchy of information within events (i.e., melodic intervals or story elements) was either attentionally highlighted or obscured by placing a varying number of accents (i.e., prolonged notes or commercial breaks) at locations that either coincided or conflicted with grammatical phrase boundaries. When subjects were unexpectedly asked to judge the actual duration of events, through a reproduction (Experiment 1) or verbal estimation (Experiment 2) task, duration estimates became more accurate and less variable when the pattern of accentuation increasingly outlined the events’ nested relationships. Conversely, when the events’ organization was increasingly obscured through accentuation, time judgments not only became less accurate and more variable, but were consistently overestimated. These findings support a theoretical framework emphasizing the effects of event structure on attending and remembering activities.     

Adults' memories of childhood: Affect,knowing, and remembering

Adult questionnaire respondents reported, for each of a number of events, if they had experienced that event during childhood and, if so, if they remembered the experience or merely knew it had happened. Respondents also rated the emotion of each event and judged whether they would remember more about each reportedly experienced event if they spent more time trying to do so. Study 1 respondents were 96 undergraduates, whereas Study 2 tested 93 community members ranging widely in age. Respondents often reported no recollections of reportedly experienced events. Reportedly experienced events rated as emotional were more often recollected than those rated as neutral, and those rated as positive were more often recollected than those rated as negative. Predicted ability to remember more was related to current memory. Claims of remembering reportedly experienced events increased with age, but predicted ability to remember more about them declined with age.     

Adults' memories of childhood: affect, knowing, and remembering

Adult questionnaire respondents reported, for each of a number of events, if they had experienced that event during childhood and, if so, if they remembered the experience or merely knew it had happened. Respondents also rated the emotion of each event and judged whether they would remember more about each reportedly experienced event if they spent more time trying to do so. Study 1 respondents were 96 undergraduates, whereas Study 2 tested 93 community members ranging widely in age. Respondents often reported no recollections of reportedly experienced events. Reportedly experienced events rated as emotional were more often recollected than those rated as neutral, and those rated as positive were more often recollected than those rated as negative. Predicted ability to remember more was related to current memory. Claims of remembering reportedly experienced events increased with age, but predicted ability to remember more about them declined with age.     

Collective memories of three wars in United States history in younger and older adults

A collective memory is a representation of the past that is shared by members of a group. We investigated similarities and differences in the collective memories of younger and older adults for three major wars in U.S. history (the Civil War, World War II, and the Iraq War). Both groups were alive during the recent Iraq War, but only the older subjects were alive during World War II, and both groups learned about the Civil War from historical sources. Subjects recalled the 10 most important events that occurred during each war and then evaluated the emotional valence, the relative importance, and their level of knowledge for each event. They also estimated the percentage of people that would share their memory of each event within their age group and the other age group. Although most historical events were recalled by fewer than 25 % of subjects, younger and older adults commonly recalled a core set of events for each war that conform to a narrative structure that may be fundamental to collective remembering. Younger adults showed greater consensus in the events that they recalled for all three wars, relative to older adults, but there was less consensus in both groups for the Iraq War. Whereas younger adults recalled more specific events of short duration, older adults recalled more extended and summarized events of long duration. Our study shows that collective memories can be studied empirically and can differ depending on whether the events are experienced personally or learned from historical sources.     

Expectancy,controlled attention and automatic attention in prospective temporal judgments

Two experiments indicate that prospective judgments of a temporal target are influenced by nontarget temporal features. The basic task was to reproduce a target interval marked by visual events. In addition, visual or auditory interfering events were delivered. Experiment 1 showed that temporal reproduction is shorter when the interfering events occupy a late rather than early position during the target interval, a result explained in terms of expectancy, which causes attention shifts. This study also revealed that similar trends are obtained whether the interfering event involves a specific task or is irrelevant. Experiment 2 confirmed the position effect, and showed that the duration of an irrelevant cue can influence judgment of the target interval, as if it were also timed without appropriate control.     

Temporal memory of emotional experience

The few studies that have investigated judgments of time have suggested that the memory of duration is distorted more for emotional events than for neutral events, while in contrast there is abundant evidence that other aspects of memories of emotional events are more accurate. To reconcile this apparent discrepancy, we used a procedure in which the participants learned a standard duration over several trials under three emotional conditions: a threatening, a nonthreatening, and a neutral control condition. They were then tested either immediately or 24 h after learning. In this test phase, they had to indicate whether presented comparison durations were or were not the same as the previously learned standard duration. We found that durations were recalled better in the emotional than in the neutral condition, and that this occurred to a greater extent in the threatening than in the nonthreatening condition. Arousing emotions thus enhanced temporal memory, just as they enhance memory for other aspects of emotional events.     

The role of learning in remembered duration

In two experiments, the effects of learning on both the accuracy and bias of duration judgments were examined. In Experiment 1, subjects learned one of two tasks (i.e., using a computer software package, building a model car), containing a varying number of action steps, over a one-, three-, or five-trial period. Retrospective judgments of a task’s total duration revealed that accuracy was high at intermediate stages of learning but was low at early stages due to an overestimation bias and low at later stages due to an underestimation bias. The number of action steps within a task influenced behavior only at early learning stages where more action steps led to significantly longer duration estimates. Experiment 2 acted as a converging operation in which novice and experienced pianists were asked to estimate, in advance, how long they thought it would take them to play melodies that varied in their degree of familiarity (i.e. recently learned, well learned, extremely well learned). When these estimates were compared with the melodies’ actual playing times, results revealed a similar pattern of accuracy and bias as found in Experiment 1. These findings are discussed in terms of a “structural remembering model” that emphasizes the role of event predictability in time estimation behavior.     

Does familiarity affect transfer from an iconic to a short-term memory?

Six Ss discriminated seven-letter nonsense words from comparison words. Target and comparison words differed on randomly selected trials by one randomly chosen letter. Target words were displayed for 50, 55, 60, 70, 90, or 200 msec, and were preceded and followed by a masking field. In one condition the Ss were familiarized with the comparison words, and in another they were not. Discrimination was better for familiar words at all display durations. There was an interaction between familiarity and the letter position effect. For unfamiliar words the typical bow-shaped position effect occurred. For familiar words no marked position effect occurred. An identification condition using unfamiliar words found no interaction between letter position and display duration. The results are interpreted as evidence that familiarity removes a letter position effect that depends upon serial transfer from a nonmaskable mediating visual representation that is constructed from a maskable representation by nonserial processes.     

Temporal accent structure and the remembering of filmed narratives.

Effects of temporal accent structure on the remembering of filmed narratives were examined by varying the placement and number of commercial breaks. Commercials either highlighted a story's underlying organization by occurring between major episode boundaries (i.e., at breakpoint locations) or obscured this structural arrangement by occurring within episodes (i.e., at nonbreakpoints). Relative to the accentuation of nonbreakpoints, results indicated that the attentional highlighting of episode boundaries yielded higher recall and recognition performance and better memory for temporal order information and details from the story's plot. Selective recall and recognition of breakpoint scenes was significantly higher than that of nonbreakpoints, suggesting that people use episode boundaries as referents for attending and remembering. These findings illustrate certain structural invariants across environmental events and ways in which event structure can be used in remembering.     

Remembering from any angle: the flexibility of visual perspective during retrieval

When recalling autobiographical memories, individuals often experience visual images associated with the event. These images can be constructed from two different perspectives: first person, in which the event is visualized from the viewpoint experienced at encoding, or third person, in which the event is visualized from an external vantage point. Using a novel technique to measure visual perspective, we examined where the external vantage point is situated in third-person images. Individuals in two studies were asked to recall either 10 or 15 events from their lives and describe the perspectives they experienced. Wide variation in spatial locations was observed within third-person perspectives, with the location of these perspectives relating to the event being recalled. Results suggest remembering from an external viewpoint may be more common than previous studies have demonstrated.     

Scalar timing without reference memory? Episodic temporal generalization and bisection in humans

Three experiments tested whether the scalar property of timing could occur when humans timed short durations under conditions in which it was unlikely that they developed reference memories of temporal "standards". Experiment 1 used an episodic version of a temporal generalization task where judgements were made of the potential equality of two durations presented on each trial. Unknown to the subject, one of these was always 200, 400, 600, or 800 ms, and the other was of variable duration. Temporal generalization gradients showed the scalar property of superimposition at standard values greater than 200 ms. Experiment 2 used a variant of the "roving bisection" method invented by Rodriguez-Girones and Kacelnik (1998) modified so that the scalar property of timing could be observed empirically. Data from bisection with short/long standard pairs of 100/400, 200/800, and 300/1,200 ms showed nearly perfect scalar-type superimposition. Experiment 3 again used episodic temporal generalization, but durations were never repeated and came from three distinct time ranges. Superimposition was found across these ranges except for the shortest visual stimuli timed. The data suggested that scalar timing could occur in humans in conditions where the formation of reference memories of temporal standards was highly improbable.     

Memory for positive,negative and neutral events in younger and older adults: Does emotion influence binding in event memory?

When remembering an event, it is important to remember both the features of the event (e.g., a person and an action) and the connections among features (e.g., who performed which action). Emotion often enhances memory for stimulus features, but the relationship between emotion and the binding of features in memory is unclear. Younger and older adults attempted to remember events in which a person performed a negative, positive or neutral action. Memory for the action was enhanced by emotion, but emotion did not enhance the ability of participants to remember which person performed which action. Older adults were more likely than younger adults to make binding errors in which they incorrectly remembered a familiar actor performing a familiar action that had actually been performed by someone else, and this age-related associative deficit was found for both neutral and emotional actions. Emotion not only increased correct recognition of old events for older and younger adults but also increased false recognition of events in which a familiar actor performed a familiar action that had been performed by someone else. Thus, although emotion may enhance memory for the features of an event, it does not increase the accuracy of remembering who performed which action.     

How emotion affects older adults' memories for event details

As adults age, they tend to have problems remembering the details of events and the contexts in which events occurred. This review presents evidence that emotion can enhance older adults' abilities to remember episodic detail. Older adults are more likely to remember affective details of an event (e.g., whether something was good or bad, or how an event made them feel) than they are to remember non-affective details, and they remember more details of emotional events than of non-emotional ones. Moreover, in some instances, emotion appears to narrow the age gap in memory performance. It may be that memory for affective context, or for emotional events, relies on cognitive and neural processes that are relatively preserved in older adults.     

Attention during memory retrieval enhances future remembering

Memory retrieval is a powerful learning event that influences whether an experience will be remembered in the future. Although retrieval can succeed in the presence of distraction, dividing attention during retrieval may reduce the power of remembering as an encoding event. In the present experiments, participants studied pictures of objects under full attention and then engaged in item recognition and source memory retrieval under full or divided attention. Two days later, a second recognition and source recollection test assessed the impact of attention during initial retrieval on long-term retention. On this latter test, performance was superior for items that had been tested initially under full versus divided attention. More importantly, even when items were correctly recognized on the first test, divided attention reduced the likelihood of subsequent recognition on the second test. The same held true for source recollection. Additionally, foils presented during the first test were also less likely to be later recognized if they had been encountered initially under divided attention. These findings demonstrate that attentive retrieval is critical for learning through remembering.     

Walking through doorways differentially affects recall and familiarity

Previous research has reported that walking through a doorway to a new location makes memory for objects and events experienced in the previous location less accurate. This effect, termed the location updating effect, has been used to suggest that location changes are used to mark boundaries between events in memory: memories for objects encountered within the current event are more available than those from beyond an event boundary. Within a computer‐generated memory task, participants navigated through virtual rooms, walking through doorways, and interacting with objects. The accuracy and their subjective experience of their memory for the objects (remember/know and confidence) were assessed. The findings showed that shifts in location decreased accurate responses associated with the subjective experience of remembering but not those associated with the experience of knowing, even when considering only the most confident responses in each condition. These findings demonstrate that a shift in location selectively impacts recollection and so contributes to our understanding of boundaries in event memory.     

Relations between emotion,memory encoding,and time perception

This study examined duration judgments for taboo and neutral words in prospective and retrospective timing tasks. In the prospective task, participants attended to time from the beginning and generated shorter duration estimates for taboo than neutral words and for words that they subsequently recalled in a surprise free recall task. These findings suggested that memory encoding took priority over estimating durations, directing attention away from time and causing better recall but shorter perceived durations for taboo than neutral words. However, in the retrospective task, participants only judged durations in a surprise test at the end, and their duration estimates were longer for taboo than neutral words. Present findings therefore suggest that the same emotion-linked memory encoding processes can cause underestimation of durations in prospective tasks but overestimation in retrospective tasks, as if emotion enhances recall of ongoing events but causes overestimation of the durations of those events in retrospect.     

The effect of actual event duration and event memory on the reconstruction of duration information

Two experiments investigated the effect of actual event duration and event memory on the retrospective estimation of public event duration. Experiment 1 provided a typicality score for each of 20 public events. The typicality score represents the degree to which the event's actual duration deviates from the typical duration of its category. Subjects in Experiment 2 estimated the duration of the events used in Experiment 1 and indicated whether they remembered the events. Typicality scores were found to be highly correlated with estimation accuracy, and to predict whether event duration was under- or over-estimated. Remembering an event slightly increased estimation accuracy. The results are discussed in terms of their implications for the assessment of eyewitness retrospective duration estimation abilities, and the reconstructive model of retrospective duration estimation proposed by Burt and Kemp (1991).     

On the dynamics of implicit emotion regulation: Counter-regulation after remembering events of high but not of low emotional intensity

Valence biases in attention allocation were assessed after remembering positive or negative personal events that were either still emotionally hot or to which the person had already adapted psychologically. Differences regarding the current state of psychological adjustment were manipulated experimentally by instructing participants to recall distant vs. recent events (Experiment 1) or affectively hot events vs. events to which the person had accommodated already (Experiment 2). Valence biases in affective processing were measured with a valence search task. Processes of emotional counter-regulation (i.e., attention allocation to stimuli of opposite valence to the emotional event) were elicited by remembering affectively hot events, whereas congruency effects (i.e., attention allocation to stimuli of the same valence as the emotional event) were obtained for events for which a final appraisal had already been established. The results of our study help to resolve conflicting findings from the literature regarding congruent vs. incongruent effects of remembering emotional events on affective processing. We discuss implications of our findings for the conception of emotions and for the dynamics of emotion regulation processes.