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Pré-Publication, Document De Travail Année : 2024

Spatial and Temporal Visual Integration

Résumé

We present four psychophysics experiments investigating spatiotemporal summation in various visual contexts. The experiments are 4AFC detection tasks where a target is briefly represented in one of four known locations. Stimuli consist of targets with various spatial (0 to .9dva) or temporal (0 to 100ms) properties. Staircase procedures are used to identify luminance thresholds at which the targets are detected with 75% accuracy. Lower thresholds are taken as indictive of greater summation than higher thresholds. In the first experiment, the target stimuli consist of two probes presented with varying spatial (0 to .9dva) and temporal (0 to 100ms) separation. We find an interaction between spatial and temporal integration: as spatial separation increased, the temporal separation at which the probes are most easily detected also increased. That is, probes with moderate spatial separation are more easily detected when they also have temporal separation compared to when the two probes are presented simultaneously. In a second study, targets consist of a single probe, presented for various durations (8 to 100ms), with the aim of identifying the critical period during which complete summation occurs (e.g., Bloch’s critical duration). Similarly, a third experiment used targets presented for 8ms with varying lengths of .01 to .9dva to identify the spatial area of complete summation (e.g., Ricco’s area). A fourth study builds on the first experiment, but rather than a single target appearing in one of four locations, three targets are presented and participants identify the location which did NOT contain a target. Again, we find that for conditions with spatial separation, participants had higher lower thresholds when the probes were also temporally separated. Experiments 1 and 4 provide robust evidence that detection thresholds can be lower for temporally separated targets than for concurrently presented targets. The results from experiments 1 and 4 do not align with the Ricco area or Bloch’s critical duration. However, the results can be interpreted in terms of a facilitating effect from motion detectors. Experiment 4 suggests that this effect is the product of multiple local mechanisms, rather than due to some global motion processing.
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Dates et versions

hal-04426014 , version 1 (30-01-2024)

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Simon K Rushton, Nicholas D Martin, Martin Bossard. Spatial and Temporal Visual Integration. 2024. ⟨hal-04426014⟩
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