Michael M. Roy

Underestimating the Duration of Future Events: Memory Incorrectly Used or Memory Bias?

People frequently underestimate how long it will take them to complete a task. The prevailing view is that during the prediction process, people incorrectly use their memories of how long similar tasks have taken in the past because they take an overly optimistic outlook. A variety of evidence is reviewed in this article that points to a different, although not mutually exclusive, explanation: People base predictions of future duration on their memories of how long past events have taken, but these memories are systematic underestimates of past duration. People appear to underestimate future event duration because they underestimate past event duration.

Music can facilitate blood pressure recovery from stress

OBJECTIVES Interventions that reduce the magnitude of cardiovascular responses to stress are justified, at least in part, by the notion that exaggerated responses to stress can damage the cardiovascular system. Recent data suggest that it is worthwhile to explore, in addition to the magnitude of the cardiovascular responses during stress (reactivity), the factors that affect the return to baseline levels after the stressor has ended (recovery). This experiment examined the effect of listening to music on cardiovascular recovery. DESIGN AND METHOD Participants (N = 75) performed a challenging three-minute mental arithmetic task and then were assigned randomly to sit in silence or to listen to one of several styles of music: classical, jazz or pop. RESULTS Participants who listened to classical music had significantly lower post-task systolic blood pressure levels (M = 2.1 mmHg above pre-stress baseline) than did participants who heard no music (M = 10.8 mmHg). Other musical styles did not produce significantly better recovery than silence. CONCLUSIONS The data suggest that listening to music may serve to improve cardiovascular recovery from stress, although not all music selections are effective.

Do Dogs Resemble Their Owners

We examined whether the frequent casual reports of people resembling their pets are accurate by having observers attempt to match dogs with their owners. We further explored whether any ability of observers to make such matches is due to people selecting dogs who resemble them, in which case the resemblance should be greater for predictable purebreds than for nonpurebreds, or is due to convergence, in which case the resemblance should grow with duration of ownership. Forty-five dogs and their owners were photographed separately, and judges were shown one owner, that owners dog, and one other dog, with the task of picking out the true match. The results were consistent with a selection account: Observers were able to match only purebred dogs with their owners, and there was no relation between the ability to pair a person with his or her pet and the time they had cohabited. The ability to match people and pets did not seem to rely on any simple trait matching (e.g., size or hairiness). The results suggest that when people pick a pet, they seek one that, at some level, resembles them, and when they get a purebred, they get what they want.

Effect of Task Length on Remembered and Predicted Duration

Vierordt’s (1868) law states that when estimating the duration of a previous task, people overestimate short durations and underestimate long ones. We examine whether this same pattern holds for remembered and predicted duration for tasks lasting between 1 and 15 min. In support of Vierordt’s law and its extension to future duration estimates, task duration tended to be overestimated for short tasks (less than 2 min) and underestimated for long tasks for both remembered and predicted duration.

The relationship between affect, uses of music, and music preferences in a sample of South African adolescents

The current study examined the relationship between individual differences in uses of music (i.e. motives for listening to music), music preferences (for different genres), and positive affect (PA) and negative affect (NA), thus linking two areas of past research into a more comprehensive model. A sample of 193 South African adolescents (ages 12–17) completed measures of the above constructs and data were analyzed via correlations and structural equation modeling (SEM). Significant correlations between affect and uses of music were tested using SEM; a model whereby PA influenced background and cognitive uses of music, NA influenced emotional use of music, and higher uses of music led to increased preferences for music styles was supported. Future research for uses of music and music preferences are discussed.

Bias in memory predicts bias in estimation of future task duration

Both anecdotal accounts and experimental evidence suggest that people underestimate how long it will take them to complete future tasks. A possible reason for this tendency is that people remember tasks as taking less time than they actually did, with these biased memories causing a corresponding bias in prediction. Two experiments were performed to determine whether or not a systematic bias in memory could explain a similar systematic bias in prediction. In support, it was found that (1) the tendency to underestimate future duration disappears when the task is novel, (2) there is similar bias in estimation of both past and future durations, and (3) variables that affect memory of duration, such as level of experience with the task and duration of delay before estimation, affect prediction of duration in the same way. It appears that, at least in part, people underestimate future event duration because they underestimate past event duration.

Correcting Memory Improves Accuracy of Predicted Task Duration

People are often inaccurate in predicting task duration. The memory bias explanation holds that this error is due to people having incorrect memories of how long previous tasks have taken, and these biased memories cause biased predictions. Therefore, the authors examined the effect on increasing predictive accuracy of correcting memory through supplying feedback for actual task duration. For Experiments 1 (paper-counting task) and 2 (essay-writing task), college students were supplied with duration information about their previous performance on a similar task before predicting task duration. For Experiment 3, participants were recruited at various locations, such as fast food restaurants and video arcades, and supplied with average task duration for others before predicting how long the task would take. In all 3 experiments, supplying feedback increased predictive accuracy. Overall, results indicate that, when predicting duration, people do well when they rely not on memory of past task duration but instead on measures of actual duration, whether their own or that of others.

The influence of stress, optimism, and music training on music uses and preferences

In the present study we examined how different aspects of a person’s life, such as the amount of stress experienced, levels of optimism, and the amount of musical training received, were related to their motives for listening to music (for emotional regulation and/or for cognitive stimulation) and their preferences for what types of music to listen to. Participants (N = 154) completed surveys measuring stress, optimism, music uses, and music preferences. Results indicate that high stress ratings predicted the use of music for emotional regulation. Additionally, optimistic individuals also tended to use music emotionally, meaning that stress and optimism, though highly negatively correlated, appear to influence uses of music independently. People with more music training followed a different pattern; even though they had higher stress ratings and lower optimism ratings overall, individuals with music training tended to listen to music for cognitive reasons more than for emotional regulation. These findings help us further understand the variables that lead to individual differences in music uses and preferences.

The return trip effect: Why the return trip often seems to take less time

Three studies confirm the existence of the return trip effect: The return trip often seems shorter than the initial trip, even though the distance traveled and the actual time spent traveling are identical. A pretest shows that people indeed experience a return trip effect regularly, and the effect was found on a bus trip (Study 1), a bicycle trip (Study 2), and when participants watched a video of someone else traveling (Study 3). The return trip effect also existed when another, equidistant route was taken on the return trip, showing that it is not familiarity with the route that causes this effect. Rather, it seems that a violation of expectations causes this effect.

Dogs Still Do Resemble Their Owners

It need not be, in a rational, scientific world, that we should see the case for dogs resembling their owners as stronger than would any other observer of the available data, but it traditionally falls to the original authors to defend their original conclusions (Roy & Christenfeld, 2004), and we do so here. We also present new data, based on a new method, that support our conclusions. Levine (2005) raised an important issue concerning the nonindependence of ratings in our original study, though we suggest that the implications are not what he indicated. In our study, each dog appeared twice, once as a foil and once as the correct choice. Levine is worried that if the judges operated nonindependently across ratings, refusing, for example, to pick the same dog twice, then the expected value of getting a match right by chance could be very different from the .5 we used in our statistical analyses. However, the effect that concerns him, and that he illustrated with a small example, is attenuated in our study because we had 15, not 3, dogs in each set; because we used not 1 but 14 different presentation orders of dog-owner choices; and because judges’ actual behavior turns out to have been largely independent. (It is not logically necessary, nor even strategically advisable, for judges always to avoid picking again a dog they have previously chosen, and judges show little, albeit some, inclination to avoid this.) Although calculating the effect of these factors is mathematically formidable, it is readily examined with a computer simulation. We randomly generated 1,000 orders of dogs, each with 20,000 random ‘‘judges.’’ In the simulation, the judges were created to show the same slight tendency to avoid picking the same dog twice as the actual judges in the original study. This simulation suggests that the expected probability of getting a dog right is .5, the probability we used in our study, and that the standard error of this probability is .00005. Thus, the fear that the expected value is different from the value we chose, in either the liberal or the conservative direction, is unrealized. More subtly, nonindependence can change the distribution of scores under the null hypothesis, without changing their mean. Consider the simplest example of two owners. Nonindependent judges would get both right or both wrong, whereas independent judges, given a separate foil for each match, could get one right and one wrong. Thus, the shape of the distribution, and so the observed significance level, can change from that assumed with independent judges. This effect was attenuated in our experiment because there were 15 dogs, and also because our judges made nearly independent choices. Indeed, the computer simulation indicates that there is no cause for concern: Using the observed level of nonindependence, the simulation yielded effectively the same distribution under the null hypothesis and, therefore, the same significance of the observed effects as in the original report. Perhaps the strongest evidence, however, comes from fresh data, collected with a different method that avoids the nonindependence issue. We used 24 of the original dog and owner pictures; half the dogs were purebred, and half were not. The pictures were chosen from the original set, excluding pictures with a beach background that distinguished them from the others with a grassy park background. We also excluded two mixed-breed dogs that were close to purebred, and then reduced the number of purebreds to match the dozen nonpurebreds in the sample. For each dog, six potential owners were selected. One was the real owner, and the other five were randomly selected owners of other dogs—other purebreds in the case of a purebred picture, and nonpurebreds otherwise. With this choice of foils, any ability to match dogs with their owners would have to be based on more than just having some idea of whether a particular person was likely to own a purebred. Ninety-six new, naive judges were each shown one of the purebred dog-owners sets and one of the nonpurebred dog-owner sets, in counterbalanced order. They ranked each of the six possible owners in likelihood of being the correct match by placing slips of paper with the numbers 1 through 6 on the possible-owner photographs. No subject saw any dog or owner more than once, and each contributed only one rating to the evaluation of purebreds and one to the evaluation of nonpurebreds. For the nonpurebreds, the real owner was chosen, on average, in position 3.6, no different from the random-guessing value of 3.5, t(95) 5 0.62, p 5 .54, effect size d 5 0.06. For the Address correspondence to Nicholas J.S. Christenfeld, Department of Psychology, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0109; e-mail: nchristenfeld@ucsd.edu. PSYCHOLOGICAL SCIENCE