Abstract
This study was designed to reveal the effects of transient attention on our ability to integrate information across time —temporal integration. Previous findings regarding attentional effects on temporal processes (eg., temporal resolution, duration estimation) suggested an attentional mechanism that favors Parvo over Magno neurons. If so, attention should prolong temporal integration, because Parvo neurons typically have longer temporal integration. To test this hypothesis we measured the length of visible persistence (VP), as it assumed to reflect the length of temporal integration. Previous studies found contradicting results, none manipulated directly transient attention. Here, we combined a task that measures the length of VP with a direct manipulation of transient attention — peripheral precueing. Two squares (1×1 deg) appeared successively with a varying ISI (0–110ms). The task was to indicate whether the squares were adjacent or separated by a 0.5 deg. spatial gap, and it could only be performed when the ISI was not longer than the length of VP. This task was coupled with attentional precueing: On the “cued” trials a peripheral cue indicated the location of the squares prior to their appearance and on the “neutral” trials a neutral cue specified that the squares could appear anywhere. As predicted, attending the target location improved observers' performance, suggesting that attention indeed prolongs the length of VP. To further explore the relations between this finding and the suggested attentional mechanism, we employed several manipulations designed to set apart the influences of the Parvo and Magno systems on VP and the corresponding attentional effect. These include the manipulation of high vs. low spatial frequency (first or second order); luminance vs. isoluminance stimuli; red vs. gray background; and high vs. low contrast. We found that the length of VP, as well as the magnitude of the attentional effect, varied as a function of all manipulations.
This research was supported by THE ISRAEL SCIENCE FOUNDATION Grant (No. 925/01–1) to Y. Yeshurun.