Abstract
We addressed two questions relating to motion and attention: Firstly, is motion adaptation greater when attention is directed toward a peripheral adaptation stimulus, rather than directed to a central, motion-irrelevant stimulus? Secondly, is attention required to produce colour-contingent motion aftereffects (MAEs)? Although attention has previously been found to boost the MAE (e.g. Chaudhuri, 1990; Taya, Adams, Graf & Lavie, 2009; Kaunitz, Fracasso & Melcher, 2011), the validity of these findings has recently been questioned (Morgan, 2011, 2012). Additionally, recent work suggests that when motion and colour are misbound to produce an illusory colour-motion conjunction (as in Wu, Kanai & Shimojo, 2004) the resultant colour-contingent MAE depends on the perceived, rather than the actual contingency (Zhang & Fang, 2012, although see Blaser, Papathomas & Vidnyánszky, 2005). This result suggests that colour-motion binding may not be early and automatic, and may thus depend on attention. In the present study, observers viewed an annulus of isoluminant red and / or blue dots that moved coherently to produce clockwise or anti-clockwise motion. While this adaptation stimulus was present, observers either: (i) counted brief periods of increased motion speed, or (ii) counted light vowels amongst a stream of centrally presented light and dark letters. The difficulty of these two tasks was modulated online to maintain 75% correct performance. The resultant MAEs were quantified with test stimuli composed of red or blue dots using a nulling, staircase procedure. In agreement with previous reports, directing spatial attention to the peripheral motion stimulus increased the MAE. However, colour-contingent MAEs were observed in both the motion and letter task conditions, supporting the notion that binding of colour and motion occurs automatically.
Meeting abstract presented at VSS 2013