Two Contributions to Motion Induction: A Preattentive Effect and Facilitation due to Attentional Capture

Abstract

By combining the paradigms of motion induction (presentation of an inducing stimulus, followed after a short delay by the presentation of an elongated bar next to it) and visual search (many-item displays with or without a pop-out target), it was possible to demonstrate the existence of two separate contributions to the motion induction effect. Illusory motion in the test bar could be produced either preattentively or by facilitation due to attentional capture. The former effect is fast, independent of the delay between the inducers and the test bar and operating simultaneously at all locations across the visual display, the latter is slower (full strength in 200-300 msec) and confined to the vicinity of the pop-out inducer. The two possibly also differ in their spatial extent, the attentional capture effect extending over a larger area around the inducer. We conclude that the motion induction effect can be used to show the existence of several effects due to the sudden presentation of a visual stimulus.

Modeling the spatiotemporal cortical activity associated with the line-motion illusion in primary visual cortex

“…7 I-L). Clearly, our predictions cannot extend to very large stimuli, or stimuli with multiple cues one after another, because such stimuli may involve retinotopy, attention, or other physiological complications (14,38).…”

Perceptual consequences of visual performance fields: The case of the line motion illusion

“…Temporal acceleration by attention has been given considerable examination in the ILM literature (Hikosaka et al, 1993a, 1993b, 1993c, 1996; Kirschfeld & Kammer, 2000; Steinman et al, 1995; von Gru¨nau et al, 1996a, 1996b). This hypothesis states that exogenous attention accelerates visual processing unevenly across a limited area of the visual field, and that the acceleration decreases with greater distance from the locus of attention.…”

“…von Gru¨nau et al (1996a) conducted a series of experiments showing that both mechanisms generate ILM and that they have different time courses. The first, which they also described as “preattentive”, was able to operate at multiple locations simultaneously across a display in which 48 inducers were presented simultaneously, and in which it is highly unlikely that focal attention would be deployed.…”

“…The second mechanism, which they describe as roughly consistent with the characteristics of exogenous attention, was spatially localized and peaked in 200–300 ms. In their Experiment 2, von Gru¨nau et al (1996a) neutralized the effect of the low-level motion mechanism by placing their target stimulus equidistant between two cues in their array. This arrangement results in a percept that the line grows from both ends toward the center.…”

“…von Gru¨nau et al (1996a) have proposed that the low-level motion mechanism is more fundamental than attention in this illusion, based on its ability to generate ILM at shorter cue-stimulus SOAs than exogenous attention. This view predicts that low-level motion should account for all or the majority of the effect in this simplest case of ILM.…”