According to the time-saving bias, drivers underestimate the time saved when increasing from a low speed and overestimate the time saved when increasing from a relatively high speed. Previous research used a specific type of task — drivers were asked to estimate time saved when increasing speed and to give a numeric response — to show this. The present research conducted two studies with multiple questions to show that the time-saving bias occurs in other tasks. Study 1 found that drivers committed the time-saving bias when asked to estimate (a) the time saved when increasing speed or (b) the distance that can be completed at a given time when increasing speed or (c) the speed required to complete a given distance in decreasing times. Study 2 showed no major differences in estimations of time saved compared to estimations of the remaining journey time and also between responses given on a numeric scale versus a visual analog scale. Study 3 tested two possible explanations for the time-saving bias: a Proportion heuristic and a Differences heuristic. Some evidence was found for use of the latter.

Background: Accuracy of estimation of time-intervals has received marginal attention in psychogeriatrics. We examined presumed differences in this time measure in participants with dementia (PWD) versus participants without dementia (PWoutD), further subdivided into specific diagnoses and performance subgroups. We also studied its demographic, clinical, and cognitive correlates and predictors. A diagnostic role was hypothesized.

Methods: Forty-three individuals (27 PWD: 16 dementia of the Alzheimer's type (DAT), 11 vascular dementia (VaD); 16 PWoutD: 10 major depressive disorder (MDD), 6 normal) were interviewed with the Cambridge Examination for Mental Disorders of the Elderly – Revised (CAMDEX-R) that permits the registration of this time measure. Demographic, clinical, and cognitive data were obtained.

Results: Neither absolute accuracy of estimation of duration of interview nor its transformed logarithm were significantly different between PWD and PWoutD, or between DAT and VaD participants. MDD participants performed significantly poorer than normal and did not differ from PWD, and the PWD relatively better performing subgroup. The logarithm of absolute accuracy of estimation correlated with some clinical and cognitive variables. Only a measure of depression and of impaired judgment could significantly predict it.

Conclusions: The absolute accuracy of estimation of time-intervals did not differ between the major groups and the main diagnoses subgroups. It was associated with a variety of clinical and cognitive measures, and was predicted by the composite constructs of depression and impaired judgment. The diagnostic value of this measure in the psychogeriatric clinic is questionable, and limited to “worried” well individuals.

We investigated whether evoked potentials to omitted stimuli could be measured in rats. Such an animal model would provide a measure of aspects of information processing concerned with expectancy and time estimation. In a first experiment, omission evoked potentials (OEPs) were elicited in rats by omitting stimuli (10%) from a train of tone pips with a fixed ISI (3 s). A control session consisted of omitting stimuli (10%) from a train of tone pips with a variable ISI (2.5–3.5 s). In a second experiment, OEPs were measured in rats that received 4 mg·kg−1 diazepam or vehicle sc. In the first experiment, half of the animals showed OEPs that consisted of a late-latency positive wave, the other rats showed a slow negative drift. No OEPs were found in the control session. Rats showing OEPs consisting of a positive wave in Experiment 1 were passed to Experiment 2. In the vehicle condition of the second experiment, all rats showed OEPs. In the diazepam condition no OEPs were found. We found that OEPs can be measured in rats. In addition, OEPs are disrupted by diazepam. We propose that OEPs provide an elegant tool to elicit selectively endogenous EP components.

We studied time estimation in patients with frontal damage (F) and alcoholic Korsakoff (K) patients in order to differentiate between the contributions of working memory and episodic memory to temporal cognition. In Experiment 1, F and K patients estimated time intervals between 10 and 120 s less accurately than matched normal and alcoholic control subjects. F patients were less accurate than K patients at short (< 1 min) time intervals whereas K patients increasingly underestimated durations as intervals grew longer. F patients overestimated short intervals in inverse proportion to their performance on the Wisconsin Card Sorting Test. As intervals grew longer, overestimation yielded to underestimation for F patients. Experiment 2 involved time estimation while counting at a subjective 1/s rate. F patients' subjective tempo, though relatively rapid, did not fully explain their overestimation of short intervals. In Experiment 3, participants produced predetermined time intervals by depressing a mouse key. K patients underproduced longer intervals. F patients produced comparably to normal participants, but were extremely variable. Findings suggest that both working memory and episodic memory play an individual role in temporal cognition. Turnover within a short-term working memory buffer provides a metric for temporal decisions. The depleted working memory that typically attends frontal dysfunction may result in quicker turnover, and this may inflate subjective duration. On the other hand, temporal estimation beyond 30 s requires episodic remembering, and this puts K patients at a disadvantage. (JINS, 2000, 6, 517–528.)