Trends and styles in visual masking

Abstract

Advances in Cognitive PsychologyProcessing of nonconscious stimuli has a long history as a research topic of experimental vision research. The recent past has seen an increasing number of research articles that address questions of noncon-scious vision. One starting point for this renewed interest has been the provision of visual masking paradigms – the topic of the present edition – as powerful tools for demonstrating the processing of nonconscious visual information (cf. Neumann & Klotz, 1994; Klotz & Neumann, 1999). Neumann and Klotz impeded con-scious perception of visual stimuli (‘primes’) by tem-porally trailing, spatially adjacent visual masks (meta--contrast masking; cf. Exner, 1868; Stigler, 1910). They further demonstrated that the prime influencesspeed and accuracy of responses towards the visible mask (“metacontrast dissociation”). Since Neumann and Klotz’s original report, numerous studies have replicated the basic finding,includingdemonstrationsof priming in electrophysiological measures of re-sponse activation and the shifting of visuospatial at-tention (see, for instance, Breitmeyer, Ro, & Singhal, 2004; Eimer & Schlaghecken, 1998; Jaśkowski, van der Lubbe, Schlotterbeck, & Verleger, 2002; Leuthold & Kopp, 1998; Schaghecken & Eimer, 2004; Vorberg, Mattler, Heinecke, Schmidt, & Schwarzbach, 2003).Occasionally, the processing of conscious and nonconscious information was assumed to be ac-complished by separate systems, as for example, the dorsal and the ventral stream of the cortical visual system (Milner & Goodale, 1995). Recent results, how-ever, show that there is no single and uniform system for the processing of conscious, or the processing of nonconscious information, even in vision. Instead, it seems that nonconscious stimuli are processed partly like conscious stimuli, especially during early stages of processing, and that the processing diverges only in some respects, at later, reentrant or feedback stages (cf. Aron et al., 2003; Haynes, Driver, & Rees, 2005; Lamme & Roelfsema, 2001; Morris, Ohman, & Dolan, 1999; Ogmen & Breitmeyer, 2006; Pinel, Riviere, Le Bihan, & Dehaene, 2001). These results suggest a shifting of the research focus towards two general questions: (a) the extent to which processing of conscious and nonconscious information contributes to any specificvisualfunc-tion, and (b) the identificationoftemporalstagescharacteristic of the processing of conscious and nonconscious visual information, respectively. These research questions have been addressed in a variety of forms, concerning the temporal dynamics of prim-ing and masking, the comparison of semantic and sensorimotor processing, or the role of intentions for the processing of nonconscious information.