Intensity dependence of perceived duration: Data, theories, and neural integration.

The effects of sensory signal characteristics on the duration discrimination of intermodal intervals was investigated in three experiments. Temporal intervals were marked by either the successive presentation of a visual then auditory signal (VA), or by the successive presentation of an auditory then visual signal (AV). The results indicated that (1) VA intervals are generally easier to discriminate than are AV intervals, but this effect depends on the range of duration studied; (2) AV intervals are perceived as longer than VA intervals for durations ranging from 250 to 750 msec; (3) the intensity of the visual markers for both AV and VA intervals does not affect the discrimination; and (4) the perceived duration of an intermodal interval is influenced by the length of the first and second markers. The results are mainly interpreted in terms of (1) a sensory trace left by visual and auditory signals and (2) the detection of these signals.

Section: Discussionmentioning

confidence: 99%

Markers’ influence on the duration discrimination of intermodal intervals

Grondin

Ivry

Franz

et al. 1996

“…It is reasonable to assurne that the perceived duration for such brief stimuli is influenced by apparent intensity differences (Bloch's law) or merely by differences in sensory persistence (Long & Beaton, 1980). Though the relation of stimulus intensity and perceived duration is far from being clear (see Nisly & Wasserman, 1989), it might be that subjects based their duration ratings on perceived intensity instead of perceived duration, or it might even be possible that the precue affected only sensory persistence. To rule out such alternative explanations, Experiment 2 employed Ionger stimulus intervals.…”

Section: Methodsmentioning

confidence: 99%

Directed attention prolongs the perceived duration of a brief stimulus

Mattes

Ulrich

1998

125

115

Stelmach, Herdman, and McNeil (1994) suggested recently that the perceived duration for attended stimuli is shorter than that for unattended ones. In contrast, the attenuation hypothesis (Thomas & Weaver, 1975) suggests the reverse relation between directed attention and perceived duration. We conducted six experiments to test the validity of the two contradictory hypotheses. In all the experiments, attention was directed to one oftwo possible stimulus sources. Experiments 1 and 2 employed stimulus durations from 70to 270msec. Astimulus appeared in either the visual or the auditory modality. Stimuli in the attended modality were rated as Ionger than stimuli in the unattended modality. Experiment 3 replicated this flnding using a different psychophysical procedure. Experiments 4-6 showed that the finding applies not only to stimuli from different sensory modalities but also to stimuli appearing at different locations within the visual field. The results of all six experiments support the assumption that directed attention prolongs the perceived duration of a stimulus.Since the influential monograph by James (1890), there has been agreement that attention plays an important role in the perception oftime (Brown & West, 1990). Specifically, subjects estimate an interval to be shorter when an additional task requires the processing of nontemporal information. For example, in the classical studies ofKatz (1906), intervals ofabout 1.2 sec werejudged shorterwhen attention was distracted by an accompanying task (e.g., reading ofsyllables). Meanwhile, numerous studies have replicated and extended this basic finding with various dual-task paradigms (Grondin & Macar, 1992;Hülser, 1924; Macar, Grondin, & Casini, 1994;Predebon, 1996;Quasebarth, 1924;Thomas & Cantor, 1978;Underwood & Swain, 1973;Zakay, 1993;Zakay & Tsal, 1989).For example, Macar et al. (1994) employedan attentionalsharing method. In each trial, several words appeared within an interval of 12 or 18 sec. The words came from different semantic categories and the subjects' task was to count animal names and to reproduce the duration of the word series at the end of the trial. Subjects were asked to divide their attention between the two tasks in prespecified proportions. When more attention was devoted to the counting task, subjects underestimated the duration of the word series. In a further experiment, the authors employed a discrimination task in which subjects were presented with stimuli of varying duration and intensity and judged both stimulus dimensions. As in the Parts of this paper were presented at the annual meetings of the International Society for Psychophysics, 1994 (Vancouver, Canada) and 1996 (Padua, Italy). We thank Hiltraut Müller-Gethmann for her comments on an earlier version ofthis article and Lloyd L. Avant, Jim Enns, and Ray Klein for their insightful reviews. Correspondence should be addressed to S. Mattes, General Psychology I, Fachbereich 3, University of'Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany (email: mattes@uni-wupperta...

“…The simulations of data showing an inverse relation of persistence to flash luminance support the idea that reset of the boundary segmentation and collapse of the filled-in percept that it supports subserve this property. Data showing a direct relation of persistence to flash luminance, due to aftereffects or informational persistence of the stimuli, as in iconic or working memory storage processes (Coltheart, 1980;Nisly & Wasserman, 1989), are not simulated by this model. Figures 23 and 24 summarize illustrative comparisons between psychophysical data and model simulations.…”

Section: Synchronous Feature Binding In Visual Cortexmentioning

confidence: 99%

3-D vision and figure-ground separation by visual cortex

Grossberg

1994

419

632

A neural network theory of three-dimensional (3-D)vision, called FACADE theory, is described. The theory proposes a solution of the classical figure-ground problem for biological vision. It does so by suggesting how boundary representations and surface representations are formed within a boundary contour system (BCS) and a feature contour system (FCS). The BCS and FCS interact reciprocally to form 3-D boundary and surface representations that are mutually consistent. Their interactions generate 3-D percepts wherein occluding and occluded object parts are separated, completed, and grouped. The theory clarifies how preattentive processes of 3-D perception and figure-ground separation interact reciprocally with attentive processes of spatial localization, object recognition, and visual search. A new theory of stereopsis is proposed that predicts how cells sensitive to multiple spatial frequencies, disparities, and orientations are combined by contextsensitive filtering, competition, and cooperation to form coherent BCS boundary segmentations. Several factors contribute to figure-ground pop-out, including: boundary contrast between spatially contiguous boundaries, whether due to scenic differences in luminance, color, spatial frequency, or disparity; partially ordered interactions from larger spatial scales and disparities to smaller scales and disparities; and surface filling-in restricted to regions surrounded by a connected boundary. Phenomena such as 3-D pop-out from a 2-D picture, Da Vinci stereopsis, 3-D neon color spreading, completion of partially occluded objects, and figure-ground reversals are analyzed. The BCS and FCS subsystems model aspects of how the two parvocellular cortical processing streams that join the lateral geniculate nucleus to prestriate cortical area V4 interact to generate a multiplexed representation of Form-And-Color-And-DEpth, or FACADE, within area V4. Area V4 is suggested to support figure-ground separation and to interact with cortical mechanisms of spatial attention, attentive object learning, and visual search. Adaptive resonance theory (ART) mechanisms model aspects of how prestriate visual cortex interacts reciprocally with a visual object recognition system in inferotemporal (IT)