Steve M. J. Janssen

Memory for time: how people date events

The effect of different formats on the accuracy of dating news and the distribution of personal events was examined in four conditions. In the first, participants had to date events in the absolute time format (e.g., “July 2004”), and in the second, they had to date events in the relative time format (e.g., “3 weeks ago”). In the other conditions, they were asked to choose between the two formats. We found a small backward telescoping effect for recent news events and a large forward telescoping effect for remote events. Events dated in the absolute time format were more accurate than those dated in the relative time format. Furthermore, participants preferred to date news events with the relative time format and personal events with the absolute time format, as well as preferring to date remote events in the relative time format and recent events in the absolute time format.

The reminiscence bump in autobiographical memory: Effects of age, gender, education, and culture

We investigated the age distribution of autobiographical memories with the Galton-Crovitz method through the Internet. Almost 2000 participants in the United States and the Netherlands aged between 11 and 70 years participated. They were presented with 10 cue words, and were asked to recall and date autobiographical memories. We found strong evidence for a “reminiscence bump” in all participant groups at all ages, with peaks at ages 15–18 for men and 13–14 for women. This peak could be localised more precisely than in previous studies due to our large sample size. We were able to remove the forgetting effect from the empirical age distribution with a method that allows separate estimation of memory encoding and forgetting. American participants showed a tendency to report older memories than the Dutch. Age group and level of education did not influence the lifetime encoding function.

Reminiscence bump in autobiographical memory: Unexplained by novelty, emotionality, valence, or importance of personal events

People tend to recall a disproportionately large number of personal events from their adolescence and early adulthood. This “reminiscence bump” has been examined extensively, but its causes remain unclear. In this Internet-based experiment, nearly 3,500 participants were given 10 cue words and were asked to describe the personal events that came to mind. Furthermore, they were asked to date each event and to indicate whether it was a first-time experience. Finally, the participants were asked to rate the strength of the emotional reaction to the event or the valence or the importance of the event. Surprisingly, the reminiscence bump consisted of relatively fewer novel, emotional, important positive or negative events. This result increases the likelihood of an alternative explanation—namely, that memory is generally enhanced in adolescence and early adulthood. However, this account has not been tested directly.

Temporal distribution of favourite books, movies and records: Differential encoding and re-sampling

The reminiscence bump is the effect that people recall more personal events from early adulthood than from childhood or adulthood. The bump has been examined extensively. However, the question of whether the bump is caused by differential encoding or re-sampling is still unanswered. To examine this issue, participants were asked to name their three favourite books, movies, and records. Furthermore, they were asked when they first encountered them. We compared the temporal distributions and found that they all showed recency effects and reminiscence bumps. The distribution of favourite books had the largest recency effect and the distribution of favourite records had the largest reminiscence bump. We can explain these results by the difference in rehearsal. Books are read two or three times, movies are watched more frequently, whereas records are listened to numerous times. The results suggest that differential encoding initially causes the reminiscence bump and that re-sampling increases the bump further.

Remembering the news: Modeling retention data from a study with 14,000 participants

A retention study is presented in which participants answered questions about news events, with a retention interval that varied within participants between 1 day and 2 years. The study involved more than 14,000 participants and around 500,000 data points. The data were analyzed separately for participants who answered questions in Dutch or in English, providing an opportunity for replication. We fitted models of varying complexity to the data in order to test several hypotheses concerning retention. Evidence for an asymptote in retention was found in only one data set, and participants with greater media exposure displayed a higher degree of learning but no difference in forgetting. Thus, forgetting was independent of initial learning. Older adults were found to have forgetting curves similar to those of younger adults.

Reminiscence bump in memory for public events

People tend to recall more personal events from adolescence and early adulthood than from other lifetime periods. Most evidence suggests that differential encoding causes this reminiscence bump. However, the question why personal events are encoded better in those periods is still unanswered. To shed more light on this discussion, we examined memory for public events. Since it is often impossible to ascertain that queried events are equally difficult, we circumvented the issue of equivalence by calculating deviation scores for each trial. We found that participants more frequently answered questions correctly about events that occurred in the period in which they were between 10 and 25 years old. Furthermore, we found that the reminiscence bump was more pronounced for cued recall than for recognition. We argue that these results support the biological account that events are stored better, because the memory system is working more efficiently during adolescence and early adulthood. These results do not falsify the other accounts for differential encoding, because they are not mutually exclusive.

The rise and fall of immediate and delayed memory for verbal and visuospatial information from late childhood to late adulthood

Over 100,000 verbal and visuospatial immediate and delayed memory tests were presented via the Internet to over 28,000 participants in the age range of 11 to 80. Structural equation modeling pointed to the verbal versus visuospatial dimension as an important factor in individual differences, but not the immediate versus delayed dimension. We found a linear decrease of 1% to 3% per year in overall memory performance past the age of 25. For visuospatial tests, this decrease started at age 18 and was twice as fast as the decrease of verbal memory. There were strong effects of education, with the highest educated group sometimes scoring one full standard deviation above the lowest educated group. Gender effects were small but as expected: women outperformed men on the verbal memory tasks; men outperformed women on the visuospatial tasks. We also found evidence of increasing proneness to false memory with age. Memory for recent news events did not show a decrease with age.

Retention of autobiographical memories: an Internet-based diary study

In this online study we examined the retention of recent personal events using an Internet-based diary technique. Each participant (N=878) recorded on a website one recent personal event and was contacted after a retention interval that ranged between 2 and 46 days. We investigated how well the participants could recall the content, time, and details of their recorded event. We found a classic retention function. Details of the events were forgotten more rapidly than the content and the time of the events. There were no differences between the forgetting rates of the “who”, “what” and “where” elements of the content component. Reminiscing, social sharing, pleasantness, and frequency of occurrence aided recall, but surprisingly importance and emotionality did not. They were, however, strongly associated with reminiscing and social sharing.

Why does life appear to speed up as people get older

In this study, the influence of contemporaneous and retrospective recall of time pressure on the experience of time was examined. Participants (N = 868) first indicated how fast the previous week, month, year, and 10 years had passed. No effects of age were found, except on the 10-year interval. The participants were subsequently asked how much time pressure they experienced presently and how much time pressure they had experienced 10 years ago. Participants who indicated that they were currently experiencing much time pressure reported that time was passing quickly on the shorter time intervals, whereas participants who indicated that they had been experiencing much time pressure 10 years ago reported that the previous 10 years had passed quickly. Cross-sectional comparisons of past and present time pressure suggested that participants systematically underestimated past time pressure. This memory bias offers an explanation of why life appears to speed up as people get older.

The phenomenology and temporal distributions of autobiographical memories elicited with emotional and neutral cue words.

In this study we examined whether the temporal distribution of autobiographical memory changes when different types of cue words are used to elicit the memories, and how the type of cue word affects the phenomenal characteristics of the memories. A total of 76 participants, ranging in age from 21 to 69 years, were presented with 22 cue words (emotional, emotion-provoking, and neutral). They were asked to recall a personal event and to complete the Autobiographical Memory Questionnaire (Rubin, Schrauf, & Greenberg, 2003, 2004) for each cue word. Results showed that the phenomenological properties of autobiographical memories which were cued with emotional and emotion-provoking words were rated higher than those of memories which were cued with neutral words, and that the peak in the temporal distributions of the autobiographical memories that were cued with emotional or emotion-provoking words were located later than the peak of the distribution of the memories that were cued with neutral words.