Evidence for Object Permanence in the Smooth-Pursuit Eye Movements of Monkeys

Abstract

Evidence for object permanence in the smooth-pursuit eye movements of monkeys.

Adaptations of lateral hand movements to early and late visual occlusion in catching

“…2 equal to or larger than 400 ms (such that the target position at interception is 'known' when the occlusion starts), unless the absent motion signals are 'filled in' using ED. However, targets are continuously tracked with the eyes during interception (Brenner and Smeets 2007;Mrotek and Soechting 2007b) and although visual pursuit gain typically reduces during occlusion (Becker and Fuchs 1985;Bennett and Barnes 2003;Churchland et al 2003;Mrotek and Soechting 2007a), occluded targets are pursued. Indeed, motion-related activity in the frontal eye fields persists during occlusion (Barborica and Ferrera 2003;Xiao et al 2007).…”

“…To 'force' our participants to extrapolate ball motion we used an occlusion window of 400 ms, which is considerably longer than typical estimates of the visuomotor delay (100-200 ms, Brenner et al 1998;Saunders and Knill 2005). Due to the predominance of visual position and velocity information in motion extrapolation (Bennett and Barnes 2003;Brouwer et al 2002Brouwer et al , 2003Brouwer et al , 2005Churchland et al 2003), ball motion during the occlusion may be expected to be underestimated, resulting in a leftward movement bias at interception (see explanation above). However, given that our participants will try to catch the ball, they might adapt the extrapolation process.…”

Disappearance of the inversion effect during memory-guided tracking of scrambled biological motion

“…According to Barnes and Collins (2008), when there is a complete loss of the visual feedback signal after target disappearance, smooth pursuit continues at a reduced gain and is maintained by extraretinal information processing. It has been recognized that the extraretinal input is a more complex arrangement reflecting velocity-coded information (Barnes & Asselman, 1991;Bennett & Barnes, 2004;Churchland et al, 2003), which is influenced by cognitive factors such as perception, expectation, and attention (Beutter & Stone, 1998;Madelain & Krauzlis, 2003;Pola & Wyatt, 1997;Tanaka & Lisberger, 2001). For the four biological-motion stimuli in the present study, velocity encoding is to some extent identical, whereas identity encoding differentiated by the global configuration is different.…”

“…Previous studies have shown that the velocity gain was smaller during the occlusion phase than during the visible phase (Bennett & Barnes, 2003;Bennett et al, 2007;Churchland, Chou, & Lisberger, 2003;de Brouwer, Missal, & Lefèvre, 2001;Ding et al, 2009;Mitrani & Dimitrov, 1978), particularly when the stimuli conveyed obvious biological meaningfulness or biological significance Orban de Xivry et al, 2010). However, from the beginning to the end of the occlusion phase, the smoothpursuit velocity of observers did not reveal any significant difference between upright and inverted point-light walkers .…”

“…Extraretinal inputs may reflect several real or hypothetical influences, including efference copy (Beye velocity memory^), remembered target motion (Btarget velocity memory^), volition, attention, and expectation (Bennett & Barnes, 2004). However, when a target disappears very briefly behind an occluder, pursuit is maintained by the efference copy loop, acting as a memory of the eye velocity immediately prior to target disappearance (Churchland, Chou, & Lisberger, 2003). It has been recognized that the extraretinal input is influenced by cognitive factors such as perception, expectation, and attention (Beutter & Stone, 1998;Madelain & Krauzlis, 2003;Pola & Wyatt, 1997;Tanaka & Lisberger, 2001).…”