No abstract

Eye-tracking has been used to investigate observing responses in matching-to-sample procedures. However, in visual search, peripheral vision plays an important role. Therefore, three experiments were conducted to investigate the extent to which adult participants can discriminate stimuli that vary in size and position in the periphery. Experiment 1 used arbitrary matching with abstract stimuli, Experiment 2 used identity matching with abstract stimuli, and Experiment 3 used identity matching with simple (familiar) shapes. In all three experiments, participants were taught eight conditional discriminations establishing four 3-member classes of stimuli. Four different stimulus sizes and three different stimulus positions were manipulated in the 12 peripheral test phases. In these test trials, participants had to fixate their gaze on the sample stimulus in the middle of the screen while selecting a comparison stimulus. Eye movements were measured with a head-mounted eye-tracker during both training and testing. Experiment 1 shows that participants can discriminate small abstract stimuli that are arbitrarily related in the periphery. Experiment 2 shows that matching identical stimuli does not affect discrimination in the periphery compared to arbitrarily related stimuli. However, Experiment 3 shows that discrimination increases when stimuli are well-known simple shapes.

The purpose of the present experiments was to investigate stimulus control to the individual elements of multiple compound stimuli in a matching-to-sample (MTS) procedure. In Experiment 1, 20 participants were trained in a 0-s delayed identity MTS procedure with four compound stimuli before a test. In the testing condition, all aspects of the compound stimuli were presented simultaneously. The result shows that eight participants respond systematically to only one aspect of the initial compound stimuli. In Experiment 2, 20 participants in two groups were trained in the same manner as in Experiment 1. Group 1 was trained with 0-s delay and Group 2 with 3-s delay. In the test, only one compound stimulus was tested on each trial. Results show that eight and four participants in Group 1 and 2, respectively, respond systematically to one aspect of the compound stimuli.