We investigated how the performance of a color-singleton search (the search for a single odd-colored item among homogeneously colored distractors) left a persistent memory trace (lasting up to six intervening trials or approximately 17 sec) that facilitated a subsequent color-singleton search (when the same target-distractor color combination was repeated). Specifically, we investigated the roles of attention in the encoding and "retrieval" stages of this priming effect by intermixing trials in which the target location was precued by an onset cue. We found that the encoding of both target and distractor colors was automatic in that whether or not observers had to use color in locating the target in the preceding trial did not substantially affect priming. However, priming required that the color-singleton item be attended in the preceding trial. Once a color singleton display was encoded, our results indicated that priming facilitated the direction of attention to the color-singleton target on a subsequent trial. In short, when a color-singleton item happened to be a critical item to be attended in one situation, another color-singleton item defined by the same color combination tended to attract attention in subsequent encounters.

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Links between attention and emotion were investigated by obtaining electrophysiological measures of attentional selectivity together with behavioural measures of affective evaluation. Participants were asked to rate faces that had just been presented as targets or distractors in a visual search task. Distractors were rated as less trustworthy than targets. To study the association between the efficiency of selective attention during visual search and subsequent emotional responses, the N2pc component was quantified as a function of evaluative judgments. Evaluation of distractor faces (but not target faces) covaried with selective attention. On trials where distractors were later judged negatively, the N2pc emerged earlier, demonstrating that attention was strongly biased towards target events, and distractors were effectively inhibited. When previous distractors were judged positively, the N2pc was delayed, indicating unfocused attention to the target and less distractor suppression. Variations in attentional selectivity across trials can predict subsequent emotional responses, strongly suggesting that attention is closely associated with subsequent affective evaluation.

Extensive research on local color aftereffects has revealed perceptual consequences of opponent color coding in the retina and the LGN, and of orientation-and/or spatial-frequency-contingent color coding in early cortical visual areas (e.g., V1 and V2). Here, we report a color aftereffect that depends crucially on global-form-contingent color processing. Brief viewing of colored items (passively viewed, ignored, or attended) reduced the salience of the previewed color in a subsequent task of color-based visual search. This color-salience aftereffect was relatively insensitive to variations (between color preview and search) in local image features, but was substantially affected by changes in global configuration (e.g. the presence or absence of perceptual unitization); the global-form dependence of the aftereffect was also modulated by task demands. The overall results suggest that (1) color salience is adaptively modulated (from fixation to fixation), drawing attention to a new color in visual-search contexts, and (2) these modulations seem to be mediated by global-form-and-color-selective neural processing in mid to late stages of the ventral visual pathway (e.g., V4 and IT), in combination with task-dependent feedback from higher cortical areas (e.g., prefrontal cortex).

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