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Matthew Heath, Kristina Neely, Jason Yakimishyn, Gord Binsted; Visuomotor performance and visuomotor memory operate without conscious awareness of intrinsic target features. Journal of Vision 2008;8(6):613. doi: https://doi.org/10.1167/8.6.613.
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Binsted et al. (2007: Proc Natl Acad Sci USA) recently showed that unconsciously presented intrinsic target information (i.e., size) supports visuomotor control. In the present investigation, we sought to determine whether unconscious target information represents an evanescent or temporally durable visuomotor characteristic. To accomplish that objective, we used a variant of Di Lollo et al's (2000: J Exp Psychol Gen) four-dot masking paradigm. Participants were briefly (13 ms) presented an array of differently sized circles (1.5, 2.5, 3.5, 4.5, 5.5 cm). The array included a target circle identified by four red circles (i.e., four-dot mask) that surrounded but did not touch the target. During prime trials, the array and four-dot mask disappeared simultaneously, whereas during mask trials the four-dot mask remained visible for 320 ms after blanking of the circles array. Participants verbally reported the size of the target and in a separate set of trials pointed to the centre of the target. Importantly, reaches were cued in time with onset of the circles array or 1000 and 2000 ms following array presentation; that is, after a period of visual delay. Verbal reports of target size were accurate during prime but not mask trials. For reaching responses however, trajectories (e.g., reaction time, movement time, peak velocity) scaled in relation to the size of the target across prime and mask trials and regardless of whether reaches were cued in time with the array or following a period of visual delay. These results indicate that a conscious visual precept is not necessary to support motor output and that unconscious target information persists for up to 2000 ms of visual delay. As such, the present data provide a convergent view of a visual system that is largely unavailable to and unreliant on conscious awareness.
Supported by NSERC.
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