Abstract
Visual working memory, a system for temporary storage and manipulation of visual information, is strictly limited in capacity. Similarly, humans' ability to track is limited to only a few individual items at a time. We hypothesized that there is a common source of these limitations. Our working hypothesis was that capacity limitations originate at the encoding stage and are a general property of the visual system. We tested our prediction using response priming, a paradigm that differs substantially from both working memory and object tracking paradigms. It requires fast motor responses and rapid processing of visual information. Evidence also suggests that response priming requires intact retinogeniculostriate pathway. We hypothesized that priming is limited by the representation of visual information at the encoding stage. We tested participants in two experiments; the first experiment presented bars of different orientations and second experiment used different shapes. Participants made speeded responses to targets displayed at the center of the display. Prior to target presentation, a prime was presented at one of the eight positions around the imaginary circle. We varied the number of items on the screen by presenting a single prime together with distractors. Priming effects were the strongest for a single prime, presented in isolation. As the number of distractors increased, priming effects become progressively weaker and with the set size of six, were eliminated altogether. These results suggest that the capacity of visual system to represent individual objects for priming is similar to restrictions previously demonstrated for working memory. Furthermore, because response priming is independent of visual awareness, our results indicate that capacity limitations of our visual systems are not restricted to conscious vision.
Meeting abstract presented at VSS 2017