Constraints on attentional orienting by symbolic and abrupt onset cues as revealed through masking

Previous research suggests that the exogenous orienting of spatial attention is an involuntary process; that is, it can occur without intent, effort or awareness. Recent studies, however, have shown that exogenous shifts of attention may, at least to some extent, be reliant on these three factors. On the basis of this finding, the purpose of the present thesis was to tease apart the relative contribution of intentions and conscious awareness, in particular, on the orienting of attention by abrupt onset cues in the periphery and symbolic (i.e., averted eye-gaze and arrow) cues at fixation. To investigate this issue, a visual masking paradigm was used and the task-relevance of cues was manipulated. It was found in Study 1 that both masked and unmasked abrupt onset cues produce a validity effect even when they are uninformative of target location. This pattern of results indicates that abrupt onset cues can exogenously shift attention regardless of intentions and conscious awareness. It was found in Studies 2 – 4 that masked symbolic cues also produce a validity effect when they are uninformative of target location. This effect, however, was restricted to experimental contexts that favoured cue utilization and tasks that allowed for the formation of stimulus-response mappings. Intriguingly, however, this pattern of results did not hold for unmasked symbolic cues. Those cues produced a validity effect regardless of task-relevance and task-type. The findings of Studies 2 – 4, therefore, suggest that the propensity to which symbolic cues shift attention relies on participants having a conscious appreciation of the orienting stimulus. Thus, the findings of the present thesis serve to further our understanding of the constraints imposed on the orienting of visual attention generated by masked abrupt onset and symbolic cues.