Adult subjects were presented with two auditory stimuli per trial, and their task was to decide which ofthe two was longer in duration. An adaptive psychophysical procedure was used. In Experiments 1, 2, and 4, the base duration was 50 msec, whereas in Experiment 3, the base duration was 1 sec. In Experiments 1,2, and 4, it was found that filled intervals (continuous tones) were discriminated more accurately than empty intervals (with onset and offset marked by clicks). It was concluded that this difference was perceptual rather than cognitive in nature, since performance on filled and empty intervals was not affected by increasing cognitive load in a dual-task procedure (Experiment 2) but was affected by backward masking (Experiment 4). In contrast, the results of Experiment 3 showed that duration discrimination of filled auditory intervals oflonger duration was cognitively influenced, since performance was impaired by increasing cognitive load. Implications for notions of perceptual processing and timing mechanisms underlying differences in duration discrimination with filled and empty intervals are discussed.There are two types of stimuli used in time perception studies. One type is the empty (silent) interval and the other type is the filled interval. In auditorily marked empty intervals, for example, only the onset and the offset of the interval are marked by clicks, whereas in filled intervals, a tone or noise burst is presented continuously throughout the interval. Thus, in empty intervals, there is no auditory stimulus presented during the interval itself. Surprisingly, there are very few published studies on the influence of filled versus empty intervals on performance in time perception experiments involving brief intervals (i.e., intervals less than 1 sec in duration).In her review article, Allan (1979) suggested that given the results of two duration-discrimination studies reported by Abel (1972aAbel ( , 1972b, one can conclude that performance with filled intervals appears to be more accurate than performance with empty intervals. However, this comparison was not the focus of Abel's studies. In a study by Craig (1973), subjects had to adjust the time between two lOOO-Hz tones until it appeared equal in duration to the first tone. Craig found a constant error in the percepPortions of this research were presented at the annual convention of the American Psychological Association, in San Francisco, August 1991. Preparation of this article was supported by NIH Grant AG09130-01 to Susan O. Lima. We thank Lester Krueger, Lorraine Allan, and Lloyd Avant for helpful comments. Correspondence may be addressed to Thomas H. Rammsayer, Department of Psychology, University of Giessen, Otto-Behaghel Str. lOF, 0-6300 Giessen, Germany (e-mail: Thoram@DGIHRZOI.bitnet).tion of empty intervals relative to filled intervals. This finding joins those of Abel (1972aAbel ( , 1972b in suggesting that performance on filled intervals is more accurate than performance on empty intervals. Although Craig concluded that different ...

This article assesses whether the two-alternative forced-choice (2AFC) and the reminder tasks (i.e., method of constant stimuli) yield identical estimates of the difference limen (DL). In a series of six experiments, participants discriminated between two duration stimuli. Experiments 1-5 employed auditory stimuli, and Experiment 6 employed visual stimuli. Experiments 1 and 2 combined each of the two tasks with an adaptive and a nonadaptive procedure for threshold estimation. Experiment 3 varied the distribution of the comparison levels, whereas Experiment 4 employed random interstimulus intervals. Experiments 5 and 6 examined the influence of the presentation order of the standard and comparison stimuli. Results indicate that both the adaptive and the nonadaptive procedures yield virtually identical DL estimates; yet, the 2AFC task produces consistently larger DLs than does the reminder task. In addition, DL increases when the standard occurs in the second rather than in the first stimulus position. In order to account for these results, we assume that participants use an internal standard instead of the actually presented standard as a reference for their judgment.

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Temporal information processing is a fundamental brain function, which might include central timekeeping mechanisms independent of sensory modality. Psychopharmacological and patient studies suggest a crucial role of the basal ganglia in time estimation. In this study, functional magnetic resonance imaging (fMRI) was applied in 15 healthy right-handed male subjects performing an auditory time estimation task (duration discrimination of tone pairs in the range of 1,000-1,400 ms) and frequency discriminations (tone pairs differing in pitch, around 1,000 Hz) as an active control task. Task difficulty was constantly modulated by an adaptive algorithm (weighted up-down method) reacting on individual performance. Time estimation (vs rest condition) elicited a distinct pattern of cerebral activity, including the right medial and both left and right dorsolateral prefrontal cortices (DLPFC), thalamus, basal ganglia (caudate nucleus and putamen), left anterior cingulate cortex, and superior temporal auditory areas. Most activations showed lateralisation to the right hemisphere and were similar in the frequency discrimination task. Comparing time and frequency tasks, we isolated activation in the right putamen restricted to time estimation only. This result supports the notion of central processing of temporal information associated with basal ganglia activity. Temporal information processing in the brain might thus be a distributed process of interaction between modality-dependent sensory cortical function, the putamen (with a timing-specific function), and additional prefrontal cortical systems related to attention and memory. Further investigations are needed to delineate the differential contributions of the striatum and other areas to timing.

Three experiments assessed whether perceived stimulus duration depends on whether participants process an expected or an unexpected visual stimulus. Participants compared the duration of a constant standard stimulus with a variable comparison stimulus. Changes in expectancy were induced by presenting one type of comparison more frequently than another type. Experiment 1 used standard durations of 100 and 400 ms, and Experiments 2 and 3 durations of 400 and 800 ms. Stimulus frequency did not affect perceived duration in Experiment 1. In Experiments 2 and 3, however, frequent comparisons were perceived as shorter than infrequent ones, and discrimination performance was better for infrequent comparisons. Overall, this study supports the notion that infrequent stimuli increase the speed of an internal pacemaker.

Psychometric performance on different aspects of primary mental abilities (verbal comprehension, word fluency, space, closure, perceptual speed, reasoning, number and memory) was compared in 35 adult musicians and non-musicians. Significant differences could not be revealed for either mean full-scale scores or for specific aspects of intelligence, except verbal memory and reasoning. While performance on verbal memory was reliably higher for the musicians than for the non-musicians, non-musicians performed significantly better on all four subscales of Cattell’s Culture Free Intelligence Test, Scale 3. This latter finding is consistent with the assumption that musical talent may be associated more with intuitive rather than logical thinking. Musicians’ superior performance on verbal memory supports the notion that long-term musical training exerts beneficial effects on verbal memory, which is most likely due to changes in cortical organization.

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