Auras in mysticism and synaesthesia: a comparison.

In a variety of synaesthesia, photisms result from affect-laden stimuli as emotional words, or faces of familiar people. For R, who participated in this study, the sight of a familiar person triggers a mental image of "a human silhouette filled with colour". Subjective descriptions of synaesthetic experiences induced by the visual perception of people's figures and faces show similarities with the reports of those who claim to possess the ability to see the aura. It has been proposed that the purported auric perception may be easily explained by the presence of a specific subtype of cross-modal perception. We analyse the subjective reports of four synaesthetes who experience colours in response to human faces and figures. These reports are compared with descriptions of alleged auric phenomena found in the literature and with claims made by experts in esoteric spheres. The discrepancies found suggest that both phenomena are phenomenologically and behaviourally dissimilar.

Spotlight failure effect in exogenous orienting.

Many experimental results about spatial attention have been explained by assuming the existence of an attentional "spotlight" which can move from one location in visual space to another. Such an account has been recently challenged by findings which show the influence of nonspatial factors in spatial attention. In particular, the so-called "spotlight failure" effect refers to the influence of the probability of occurrence of different stimuli. However, such an effect has only been reported in the case of endogenous (or central) orientation, rather than on exogenous (or peripheral) orienting. We present evidence showing that the spotlight failure effect can be obtained with exogenous orienting, even at a short SOA (100 ms). Besides, experimental instructions can modulate the effect, which agrees with theoretical accounts proposing that top-down factors can influence attentional capture.

A more complete task-set reconfiguration in random than in predictable task switch.

Three experiments are presented that compare the cost found when switching from one task to another in two different conditions. In one of them, the tasks switch in predictable sequences. In the other condition, the tasks alternate at random. A smaller time cost is found in the random-switch condition when enough preparation time is allowed. Such an effect is due to the random-switch cost continuing to decrease with preparation time after the predictable-switch cost has reached an asymptote. Although the relationship between number of repetitions of one task and time cost is different in the random- and the predictable-switch conditions, only the latter shows the presence of an "exogenous" component of cost. The implications of this finding are discussed in relationship with the usual distinction between an endogenous component of switch cost that is affected by preparation time and another exogenous, residual component (e.g., Rogers & Monsell, 1995). It is proposed that a different kind of task-set preparation is at work when tasks alternate at random.

Does IOR occur in discrimination tasks? Yes, it does, but later.

When a stimulus appears in a previously cued location several hundred milliseconds after the cue, the time required to detect that stimulus is greater than when it appears in an uncued location. This increase in detection time is known as inhibition of return (IOR). It has been suggested that IOR reflects the action of a general attentional mechanism that prevents attention from returning to previously explored loci. At the same time, the robustness of IOR has been recently disputed, given several failures to obtain the effect in tasks requiring discrimination rather than detection. In a series of eight experiments, we evaluated the differences between detection and discrimination tasks with regard to IOR. We found that IOR was consistently obtained with both tasks, although the temporal parameters required to observe IOR were different in detection and discrimination tasks. In our detection task, the effect appeared after a 400-msec delay between cue and target, and was still present after 1,300 msec. In our discrimination task, the effect appeared later and disappeared sooner. The implications of these data for theoretical accounts of IOR are discussed.