Attention and the detectability of weak taste stimuli

Subjects detected weak solutions of sucrose or citric acid under conditionsin which attention was directed toward one of the tastants or the other.Detection thresholds were measured using an adaptive, forced-choiceprocedure, with a three-down one-up rule, which computer simulationssuggest should be more reliable than the popular two-down one-up rule. Thethresholds were modestly but systematically lower for attended tastantsthan for unattended ones. Similar results have been reported in other sensemodalities, including vision (greater sensitivity to stimuli presented toattended versus unattended spatial locations) and hearing (greatersensitivity to stimuli presented at attended versus unattended soundfrequencies). Taken together, the findings are consistent with a generalhypothesis regarding attention in sensory systems: gains or losses indetectability occur when a central attentional mechanism (or, conceivably,a preattentive mechanism) selectively and preferentially monitors signalsarising from particular subsets of peripheral neural inputs.