事件时间估计偏差理论述

人们总是倾向低估完成某一任务的时间。计划谬误理论认为,时间低估倾向的原因是人们估计时间时忽视过去完成类似任务的经验,过于关注理想的任务计划和任务情景,从而导致乐观的时间估计。但是基于该理论的一些提高时间估计精确性的策略没有达到预期效果。针对这种不足,记忆偏差理论认为,人们利用的时间记忆带有偏差,从而导致偏差的时间估计。两个理论之间引起一些争论,但如果从解释水平理论的角度可以找到其相通之处     

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.     

相似任务经验和未来时间充裕感对计划失误的影响

本研究检验了人们一种潜在的认知倾向,即低估任务的完成时间。本研究分为2个实验,从两个角度来研究人们低估任务时间的行为。实验一从不同预测方式的角度,检验了任务的相似性和认知需求因素对任务时间估计的影响。实验二从未来时间知觉的角度,检验了未来时间充裕感对任务的完成时间预测的影响。结果表明:不同的时间预测方式都会引起对任务完成/持续时间的低估;任务的相似性会利于任务时间估计的精确性;认知需求因素会和任务的相似性产生交互作用,从而影响任务完成时间的估计;未来时间充裕感的程度也会影响人们对当前任务的预测。     

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. (PsycINFO Database Record (c) 2008 APA, all rights reserved).     

Planning, personality, and prediction: The role of future focus in optimistic time predictions

The present studies examined cognitive processes underlying the tendency to underestimate project completion times. Two experiments tested the hypothesis that people generate overly optimistic predictions, in part, because they focus narrowly on their future plans for the target task and thus neglect other useful sources of information. Consistent with the hypothesis, instructing participants to adopt a “future focus”—in which they generated concrete, specific plans for the task at hand—led them to make more optimistic predictions about when they would complete their intended Christmas shopping (Study 1) and major school assignments (Study 2). The future focus manipulation did not have a corresponding effect on actual completion times, and thus increased the degree of optimistic bias in prediction. The studies also demonstrated that the optimistic prediction bias generalized across different task domains, relevant individual differences (i.e., trait optimism and procrastination), and other contextual variations.     

Perspectives on prediction: Does third-person imagery improve task completion estimates?

People typically underestimate the time necessary to complete their tasks. According to the planning fallacy model of optimistic time predictions, this underestimation occurs because people focus on developing a specific plan for the current task and neglect the implications of past failures to meet similar deadlines. We extend the classic planning fallacy model by proposing that a phenomenal quality of mental imagery – the visual perspective that is adopted – may moderate the optimistic prediction bias. Consistent with this proposal, participants in four studies predicted longer completion times, and thus were less prone to bias, when they imagined an upcoming task from the third-person rather than first-person perspective. Third-person imagery reduced people’s focus on optimistic plans, increased their focus on potential obstacles, and decreased the impact of task-relevant motives on prediction. The findings suggest that third-person imagery helps individuals generate more realistic predictions by reducing cognitive and motivational processes that typically contribute to bias.     

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.     

Adaptive Anchoring Model: How Static and Dynamic Presentations of Time Series Influence Judgments and Predictions

When attempting to predict future events, people commonly rely on historical data. One psychological characteristic of judgmental forecasting of time series, established by research, is that when people make forecasts from series, they tend to underestimate future values for upward trends and overestimate them for downward ones, so‐called trend‐damping (modeled by anchoring on, and insufficient adjustment from, the average of recent time series values). Events in a time series can be experienced sequentially (dynamic mode), or they can also be retrospectively viewed simultaneously (static mode), not experienced individually in real time. In one experiment, we studied the influence of presentation mode (dynamic and static) on two sorts of judgment: (a) predictions of the next event (forecast) and (b) estimation of the average value of all the events in the presented series (average estimation). Participants' responses in dynamic mode were anchored on more recent events than in static mode for all types of judgment but with different consequences; hence, dynamic presentation improved prediction accuracy, but not estimation. These results are not anticipated by existing theoretical accounts; we develop and present an agent‐based model—the adaptive anchoring model (ADAM)—to account for the difference between processing sequences of dynamically and statically presented stimuli (visually presented data). ADAM captures how variation in presentation mode produces variation in responses (and the accuracy of these responses) in both forecasting and judgment tasks. ADAM's model predictions for the forecasting and judgment tasks fit better with the response data than a linear‐regression time series model. Moreover, ADAM outperformed autoregressive‐integrated‐moving‐average (ARIMA) and exponential‐smoothing models, while neither of these models accounts for people's responses on the average estimation task.     

Focalism: a source of durability bias in affective forecasting

The durability bias, the tendency to overpredict the duration of affective reactions to future events, may be due in part to focalism, whereby people focus too much on the event in question and not enough on the consequences of other future events. If so, asking people to think about other future activities should reduce the durability bias. In Studies 1-3, college football fans were less likely to overpredict how long the outcome of a football game would influence their happiness if they first thought about how much time they would spend on other future activities. Studies 4 and 5 ruled out alternative explanations and found evidence for a distraction interpretation, that people who think about future events moderate their forecasts because they believe that these events will reduce thinking about the focal event. The authors discuss the implications of focalism for other literatures, such as the planning fallacy.     

A timing-specific memory distortion effect in young children

It has been suggested that there are systematic distortions in children's memory for temporal durations, such that children's memory is not just less accurate than that of adults but qualitatively different. Experiment 1 replicated the memory distortion effect by demonstrating developmental change in the tendency to confuse a reference duration with one that is shorter rather than longer than it. When the long-term memory demands of the task were reduced by providing reminders of the reference duration on every trial, there were no such qualitative changes in error patterns (Experiment 2). Further evidence for developmental changes in memory distortion was found in the temporal generalization task of Experiment 3, in which stimuli were spaced logarithmically rather than linearly. In Experiment 4, a similar distortion pattern was absent in a task in which children made judgments about the pitch rather than the duration of stimuli, suggesting the effect may be specific to time estimation.     

Age-related positivity effects and autobiographical memory detail: Evidence from a past/future source memory task

This study investigated whether the age-related positivity effect strengthens specific event details in autobiographical memory. Participants retrieved past events or imagined future events in response to neutral or emotional cue words. Older adults rated each kind of event more positively than younger adults, demonstrating an age-related positivity effect. We next administered a source memory test. Participants were given the same cue words and tried to retrieve the previously generated event and its source (past or future). Accuracy on this source test should depend on the recollection of specific details about the earlier generated events, providing a more objective measure of those details than subjective ratings. We found that source accuracy was greater for positive than negative future events in both age groups, suggesting that positive future events were more detailed. In contrast, valence did not affect source accuracy for past events in either age group, suggesting that positive and negative past events were equally detailed. Although ageing can bias people to focus on positive aspects of experience, this bias does not appear to strengthen the availability of details for positive relative to negative past events.     

Is the interference between memory processing and timing specific to the use of verbal material?

Increasing load in a memory task performed simultaneously with a timing task shortens perceived time, an effect that has been observed previously with memory tasks using verbal material. The present experiments examine whether two similar memory tasks, one in which verbal material is used and another one in which nonverbal material is used, would produce similar interference effects on concurrent time reproduction. In Experiment 1, the number of nonverbal stimuli (pseudo‐random dot patterns) was manipulated in a memory task performed while a temporal interval to be reproduced was encoded. Reproductions shortened proportionally to the duration of memory processing executed during time estimation. Verbal stimuli (consonants) were used in Experiment 2 in otherwise identical experimental conditions. Effects observed in Experiment 2 were comparable to those obtained in Experiment 1. Taken together, these results support the notion that interference from memory tasks on concurrent time estimation is not determined by the specific type of material processed in memory, but instead by the duration of memory processing.     

Is the interference between memory processing and timing specific to the use of verbal material?

Increasing load in a memory task performed simultaneously with a timing task shortens perceived time, an effect that has been observed previously with memory tasks using verbal material. The present experiments examine whether two similar memory tasks, one in which verbal material is used and another one in which nonverbal material is used, would produce similar interference effects on concurrent time reproduction. In Experiment 1, the number of nonverbal stimuli (pseudo-random dot patterns) was manipulated in a memory task performed while a temporal interval to be reproduced was encoded. Reproductions shortened proportionally to the duration of memory processing executed during time estimation. Verbal stimuli (consonants) were used in Experiment 2 in otherwise identical experimental conditions. Effects observed in Experiment 2 were comparable to those obtained in Experiment 1. Taken together, these results support the notion that interference from memory tasks on concurrent time estimation is not determined by the specific type of material processed in memory, but instead by the duration of memory processing.     

Age-related positivity effects and autobiographical memory detail: evidence from a past/future source memory task

This study investigated whether the age-related positivity effect strengthens specific event details in autobiographical memory. Participants retrieved past events or imagined future events in response to neutral or emotional cue words. Older adults rated each kind of event more positively than younger adults, demonstrating an age-related positivity effect. We next administered a source memory test. Participants were given the same cue words and tried to retrieve the previously generated event and its source (past or future). Accuracy on this source test should depend on the recollection of specific details about the earlier generated events, providing a more objective measure of those details than subjective ratings. We found that source accuracy was greater for positive than negative future events in both age groups, suggesting that positive future events were more detailed. In contrast, valence did not affect source accuracy for past events in either age group, suggesting that positive and negative past events were equally detailed. Although ageing can bias people to focus on positive aspects of experience, this bias does not appear to strengthen the availability of details for positive relative to negative past events.     

The broad applicability of memory bias and its coexistence with the planning fallacy: reply to Griffin and Buehler (2005)

People chronically underestimate how long tasks will take. In their original article, the present authors (M. M. Roy, N. J. S. Christenfeld, & C. R. M. McKenzie, suggested a simple, broadly applicable explanation: Biased predictions result from biased memories. In their comment article, D. Griffin and R. Buehler suggested that in many domains in which this memory-bias account appears to out-predict their own account, theirs actually makes no prediction at all. However, the present authors did not suggest that only 1 theory is right but that theirs is consistent with data that prior theories, including their own, cannot explain. Ignoring memories of past tasks is not a complete explanation for the phenomenon if the memories people could consult are themselves biased. Nonetheless, underestimating future task duration is almost certainly multiply determined, and thus our account and theirs can coexist.     

Remembering the past and imagining the future: Differences in event specificity of spontaneously generated thought

A growing interest has emerged in the role that autobiographical memory retrieval plays in simulation of future events. Cognitive explorations in this domain have generally relied on cue word paradigms with instructions to develop specific (relating to one particular day) memories or future events. However, the usefulness of this paradigm has been questioned with respect to its ability to assess habitual patterns of retrieval within autobiographical memory. The current study investigated similarities and differences in how participants spontaneously remember the past and imagine the future when the specificity constraints inherent in the cue word task are removed. A total of 93 undergraduate students completed two sentence-completion tasks, probing for past and future events. A number of differences emerged between past and future thought; in particular, they were less specific when simulating future events compared with past events. This reduction in specificity was the result of participants producing more future thoughts relating to extended lifetime periods and semantic associates. The findings are discussed in relation to the underlying cognitive processes involved in autobiographical memory retrieval and future event simulation.     

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.     

How long will it take? Power biases time predictions

People tend to underestimate the time it takes to accomplish tasks. This bias known as the planning fallacy derives from the tendency to focus attention too narrowly on the envisaged goal and to ignore additional information that could make predictions more accurate and less biased. Drawing on recent research showing that power induces attentional focus, four studies tested the hypothesis that power strengthens the tendency to underestimate future task completion time. Across a range of task domains, and using multiple operationalizations of power, including actual control over outcomes (Study 1), priming (Studies 2 and 3), and individual differences (Study 4), power consistently led to more optimistic and less accurate time predictions. Support was found for the role of attentional focus as an underlying mechanism for those effects. Differences in optimism, self-efficacy, and mood did not contribute to the greater bias in powerful individuals’ forecasts. We discuss the implications of these findings for institutional decision processes and occupational health.     

The least likely of times: how remembering the past biases forecasts of the future

Atypical events are both memorable and unrepresentative of their class. We tested the hypotheses that (a) people tend to recall atypical instances of events, and (b) when they are unaware of this, they rely on these atypical instances in forecasting their affective reactions to future events. In three studies, participants who were asked to recall an instance of an event and participants who were asked to recall an atypical instance of an event recalled equally atypical instances. However, only the former participants made extreme forecasts about their reactions to future events. The results suggest that the impact bias (the tendency to overestimate the affective impact of future events) may be due in part to people's reliance on highly available but unrepresentative memories of the past.     

判断与决策中的规划谬误

规划谬误是指人们在估计未来任务的完成时间时, 倾向于过度乐观, 低估任务完成时间的一种现象。规划谬误的心理机制主要包括规划谬误理论和记忆偏差理论。规划谬误的影响因素主要有认知因素、动机因素、个体的经验水平、目标任务的性质等。规划谬误的应对策略主要有与过去的经验相联系、从第三人称视角进行估计、任务分解及时间分配。未来的研究主要从规划谬误与策略性误解、乐观偏差、过分自信的关系, 规划谬误的产生根源、规划谬误的跨文化研究、规划谬误的研究范围及应用领域等方面进一步探讨。