Kyllingsbæk, Søren4; Lommel, Sven Van2; Bundesen, Claus5
1 Institut for Psykologi, Department of Psychology, Faculty of Social Sciences, Københavns Universitet2 University of Leuven3 Department of Psychology, Faculty of Social Sciences, Københavns Universitet4 Institut for Psykologi, Department of Psychology, Faculty of Social Sciences, Københavns Universitet5 Department of Psychology, Faculty of Social Sciences, Københavns Universitet
Observers were trained to search for a particular horizontal string of 3 capital letters presented among similar strings consisting of exactly the same letters in different orders. The training was followed by a test in which the observers searched for a new target that was identical to one of the former distractors. The new distractor set consisted of the remaining former distractors plus the former target. On each trial, three letter-strings were displayed, which included the target string with a probability of .5. In Experiment 1, the strings were centered at different locations on the circumference of an imaginary circle around the fixation point. The training phase of Experiment 2 was similar, but in the test phase of the experiment, the strings were located in a vertical array centered on fixation, and in target-present arrays, the target always appeared at fixation. In both experiments, performance (d’) degraded on trials in which former targets were present, suggesting that the former targets automatically drew processing resources away from the current targets. Apparently, the two experiments showed automatic attraction of visual attention by supraletter features of former target strings.