Memory and assimilation to context in delayed matching-to-sample

Abstract

This paper reports effects of short-term memory and context stimuli on recognition of visual stimuli. After presentation of a square as the target stimulus, participants had to store the target during a variable delay, until they had to identify the target within a sample of seven squares that differed systematically in size (context variation). Marked context effects (“shifts”) that occurred as responses to the test series were obtained when sets of comparison stimuli were arranged asymmetrically with respect to targets. Participants overestimated the size of the target in a set of larger comparison stimuli by choosing a larger stimulus to match the target, and vice versa (Experiment 1). This assimilation effect increased with longer delays between target offset and the onset of comparison stimuli (Experiment 2). Briefer target exposure also induced stronger assimilation (Experiment 3). The results indicated that visual short-term memory modulates (contextual) stimulus integration in delayed matching to sample. A working model of memory and contextual effects in matching is discussed