The modulatory effects of attention and spatial location on masked face-processing: insights from the reach-to-touch paradigm

In masked priming paradigms, targets are responded to faster and more accurately when preceded by subliminal primes from the same category than a different category. Intriguingly, where these congruence priming effects elicited by word and number stimuli depend on the allocation of attention, masked faces produce priming regardless of how well attention is focused. The research presented in this thesis exploits this unique property to examine the temporal dynamics of nonconscious information processing, and the factors which modulate this hidden cognitive process. Using congruence priming effects for masked faces as an index of nonconscious perception, I present four empirical studies that examine how processing below our level of conscious awareness is affected by manipulations of spatial and temporal attention. In Study 1, I show that the allocation of both spatial and temporal attention facilitates nonconscious processing at less than 350ms of stimulus-processing time. These results suggest that attention modulates nonconscious information processing in a graded fashion that mirrors its influence on the perception of consciously presented stimuli. Study 2 investigates the differential benefit of attention between the vertical hemifields, and documents the breakthrough finding that face-processing is supported better in the upper-hemifield than the lower-hemifield. Study 3 explores whether this upper-hemifield advantage generalises to recognition of a nonface object (human hands). Study 4 investigates and dispels the possibility that the pattern of vertical asymmetry effects for face-perception relates to an upward bias in participants' visuospatial attention. The final chapter of this thesis summarises the findings from these four studies and discusses their implications within a broader research context.