Visual search of expansion and contraction

Abstract

The perception of expansion/contraction in human subjects was examined with a visual search paradigm. When searching for a target defined by two-dimensional expansion among distractors defined by two-dimensional contraction, the time needed to find the target did not vary as the number of distractors was increased. However, for a target defined by two-dimensional contraction among distractors defined by two-dimensional expansion, the search time increased as a function of the number of distractors in the display. A similar search asymmetry remained between one-dimensional expansion and one-dimensional contraction, even though one-dimensional expansion was searched in a serial manner. This asymmetry between expansion and contraction reflects a basic characteristic of higher-order motion information processing.

Neural basis of multisensory looming signals

“…Concordant with these theoretical considerations, several behavioral studies reported that the perception of auditory and visual looming and receding signals differs despite identical overall stimulus energy (auditory modality: Gray, 2011;Hall and Moore, 2003;Maier and Ghazanfar, 2007;Schlauch et al, 2001;visual modality: Franconeri and Simons, 2003;Schiff et al, 1962;Takeuchi, 1997). The only discrepancy between those signals is their temporal profile: looming signals increase in amplitude or size over time whereas for receding signals the temporal pattern is reversed.…”

Visual search asymmetries in motion and optic flow fields

“…There is little previous data on search within an optic flow background. Two studies examined search for an expanding target amid contracting or deforming distractors and vice versa (Braddick & Holliday, 1991;Takeuchi, 1997), but in these experiments each local item expanded or contracted. This is not equivalent to the global expansion pattern generated by observer motion.…”

Cast shadow can modulate the judged final position of a moving target

“…The whole stimulus display with fixation cross was initially presented statically for 1,000 msec to ensure fixation. Then, the ball and the shadow moved and disappeared 200, 400, 600, 800, or 1,000 msec later (corresponding to the target's travel distances studies have reported that the human cognitive system has anisotropic sensitivity to approaching or receding motion that is defined by expanding or contracting motion (Shirai & Yamaguchi, 2004;Takeuchi, 1997) and by a cast shadow's motion (Imura, Shirai, Tomonaga, Yamaguchi, & Yagi, 2008). They showed that approaching motion is easier to detect than receding motion.…”