Modality-Specific Effects on Discrimination of Short Empty Time Intervals

Hocherman, Shraga; Ben-Dov, Gita

doi:10.2466/pms.1979.48.3.807

Cited by 9 publications

(9 citation statements)

References 5 publications

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“…Therefore, the effect is different from other phenomena like the classical filled-duration illusion or the sharing of attention between two sources of information (Allan, 1979;Thomas & Brown, 1974;Thomas & Cantor, 1978). Indeed, this effect is more like the one reported by Hocherman and Ben-Dov (1979): when an observer discriminates among empty time intervals with some sort of forced-ehoice presentation, the observer judges the first interval to be longer more often when the observer is presented with an A-V-A sequence than when presented with a V-A-V sequence.…”

Section: Discussionmentioning

confidence: 50%

Judging the relative duration of multimodal short empty time intervals

Grondin

Rousseau

1991

Perception & Psychophysics

100

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Three experiments address the cause of the different performance levels found in time discrimination of empty intervals with durations near 250 msec. Performance differed according to the kind of sensory modality that marked the intervals. With a procedure in which the type of marker was randomized from trial to trial, it was shown that variability of discrimination judgments could not be attributed entirely to the variability of the criterion on which a judgment was based. Such a randomization slightly affects discrimination but provokes a reorganization related to marker conditions of the probabilities of judging an interval to be short or long. Moreover, it was shown that within intramodal conditions, physical characteristics of markers influence the discrimination performances. To account for the results generated with different marker-type intervals at 250 msec, we propose that two types of processor may be involved in duration discrimination: one is specifically related to a given sensory modality, whereas the other is aspecific and responsible for discrimination of intermodal intervals.

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Section: Discussionmentioning

confidence: 50%

Judging the relative duration of multimodal short empty time intervals

Grondin

Rousseau

1991

Perception & Psychophysics

100

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“…Admittedly, bimodal intervals accessing a central clock more "directly" would lead to optimal performance. Surprisingly, in duration-discrimination tasks, performance levels obtained under bimodal conditions have been shown to be much lower than those obtained with empty unimodal, auditory, or visual time intervals (Fraisse, 1952;Grondin & Rousseau, 1991;Hocherman & Ben-Dov, 1979;Rousseau, Poirier, & Lemyre, 1983). At first view, such findings can be interpreted as detrimental to the notion of a central clock concept.…”

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confidence: 72%

“…Rousseau et al argued that the similarity of slopes for bimodal and unimodal functions was an indication ofa common timekeeping mechanism operating under all interval conditions, while the differences in intercept were an indication of the contribution of nontemporal processes. Most authors have considered the lower performance level with bimodal intervals as support for mixed timing interpretations (Grondin, 1993;Grondin & Rousseau, 1991;Hocherman & Ben-Dov, 1979;Rousseau & Kristofferson, 1973).That is to say,both uni-and bimodal intervals are handled by a central timing mechanism, yet bimodal intervals are not supported by efficient modality-specific encoding processes, which would reduce the variability of the discrimination performance for unimodal intervals.…”

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confidence: 99%

“…For Grondin and Rousseau (1991), however, it was the lower efficiency of the decision-making processes involved in the short/long categorization of intervals which affected bimodal duration discrimination, with the nontemporal processes increasing variability ofthe discrimination performance for bimodal intervals. Finally, Hocherman and Ben-Dov (1979) proposed that unimodal intervals were supported by more efficient memory storage.…”

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confidence: 99%

“…Following those lines, Grondin (1993) argued that the similarity of slopes for auditory and visual functions was an indication of a common timekeeping mechanism, while the difference in intercept was an indication ofthe contribution ofnontemporal processes. Hocherman and Ben-Dov (1979), Grondin and Rousseau (1991), and Grondin (1993) have proposed that auditory and visual intervals have access to time-independent modality-specific encoding processes in addition to a central timing process. The lower intercept for auditory intervals was interpreted as an indication that auditory encoding ofduration was more efficient than visual encoding.…”

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confidence: 99%

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Stop—reaction time and the internal clock

Rousseau

1996

Perception & Psychophysics

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In a stop-reaction-time (stop-RT) task, a subject is presented with a regular, isochronous sequence of brief signals separated by a constant time interval, or stimulus onset asynchrony (SOA). His/her task is to press a response key as fast as possible when the sequence stops. As the sequence Unfolds, an internal representation of the SOAduration builds up. Stop-RT is assumed to be triggered when an internal clock, operating as an "alarm clock," reaches a time criterion. Criterion setting is contingent upon variability in the SONs internal representation. In Experiment lA, stop-RT was measured for isochronous sequences ofbrieftones, light flashes, and also sequences of tones and flashes presented in regular alternation (tone-light-tone ...). Stop-RT was a linear function of SOA duration (ranging from 250 to 1,000msec), regardless of modality, supporting a "central-clock" hypothesis. On the other hand, taken together, the results of Experiments lA, 1B, 2, and 3 suggest that no internal representation of the bimodal (tone-light) SOA of alternating sequences builds up. Indeed, an alternating sequence is physically equivalent to two interlaced isochronous subsequences, one auditory and one visual. So, two internal representations, one for the auditory (tone-tone) and one for the visual (light-light) SOA, could build up, and two time criteria running "in parallel" could thus support stop-RT. To provide a critical test of parallel timing, stop-RT was measured for bimodal 5:3 polyrhythms formed by the superposition of auditory and visual isochronous sequences that had different SOAdurations (Experiment 4). Parallel timing accounted for a large proportion of variance in polyrhythmic stop-RT data. Overall findings can be accounted for by assuming a functional architecture of an internal clock in which pulses emitted by a central pacemaker are available in parallel with two modalityspecific switch-accumulator "timing modules."

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Sequence, time, or state representation: how does the motor control system adapt to variable environments?

Karniel

Mussa-Ivaldi

2003

Biol. Cybern.

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Does the observation of well-timed movements imply the existence of some internal representation of time, such as a hypothetical neural clock? Here we report the results of experiments designed to investigate whether subjects form a correct adaptive representation of mechanical environments that change in a very predictable manner. In these experiments, subjects were asked to execute arm movements over a twodimensional workspace while experiencing time-dependent disturbing forces. We provide a formal definition for time representation and conclude that our subjects didn't use time representation for motor adaptation under the tested conditions. Subjects performed arm-reaching movements in the following experiments: (1) six experiments in a sinusoidal time-varying force field; (2) six experiments in a simple sequence of alternating viscous force fields, in which the number of targets allowed for the approximation of the force by a complex state-dependent force field; and (3) six experiments in the same simple sequence of alternating viscous force fields, in which no state-dependent force field approximation was possible. We found that the subjects did not adapt to the timevarying force field and were unable to form an adequate representation of the simple sequence of force fields. In the latter case, whenever possible, they adapted to a single state-dependent field that produced forces similar to the two alternating fields. This state-dependent field produced the same forces as the applied sequence of fields only over the trajectories that subjects executed during the training phase. However, the state-dependent field was inadequate to produce the correct forces generated by the field sequence over a new set of trajectories.These results are not consistent with the hypothesis that subjects would develop a correct representation of time-dependent forces, at least under the tested circumstances. We speculate that the system responsible for adaptation of movements to external forces may be unable to employ temporal representation. While it is possible that such a representation may emerge in a more prolonged and/or intense training, our findings indicate a preference by the adaptive system to generalize based on representing dependence of external forces upon state rather than upon time.

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Modality-Specific Effects on Discrimination of Short Empty Time Intervals

Cited by 9 publications

References 5 publications

Judging the relative duration of multimodal short empty time intervals

Judging the relative duration of multimodal short empty time intervals

Stop—reaction time and the internal clock

Sequence, time, or state representation: how does the motor control system adapt to variable environments?

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