Mechanisms of Second Target Omission in Visual Search Task and in Rapid Serial Visual Presentation.

Subsequent search misses (SSM) is a second target omission after the first one was detected in visual search task. The main reasons of SSM could be recourse depletion theory and losing the second target in case of this, as in the attentional blink phenomena (AB) or error that is caused by categorization two target stimuli as the separate stimulus, as in the repetitional blindness phenomena (RB). Both phenomena observed in the rapid visual serial presentation paradigm. The AB disappears when two targets differ from distractors perceptually, while the RB disappears when two targets differ in color. In the first experiment, the role of target-distracter similarity in second target omission was investigated. This design could show the connection between the SMM and the AB phenomena. In the second experiment, the role of target-target similarity in second target omission was investigated. This design could show the connection between the RB and the SSM mechanisms, and between the AB and the SMM. The experiment involved visual search task for both experiments. 20 stimuli were displayed within each trial. Targets were defined as the specific letters, presented among other letters. On each trial, there could be two, one or no targets on the screen. In the first experiment color and size of the stimuli were varied. Targets could be equal to distractors in color and size, differ in color or size and differ in color and size. In the second experiment target stimuli could be both the same color or differs in color. Accuracy of the second target detection was analyzed for both experiments. In the first experiment, the accuracy of second target detection increased with decreasing target-distracter similarity. In the second experiment, there was no difference between two conditions. The results show, that there could be same mechanisms between the AB and SSM, while there is no connection between the SSM and the RB.