A study of the effect of structural information and familiarity in form perception.

Two experiments were carried out to investigate the influence of structural information and familiarity on the processing of visual forms. Pairs of "well" structured and nameable and "poorly" structured and non-nameable fragmented forms were employed as stimuli. The effects of structure and familiarity were assessed by manipulating the visual hemifield of presentation and the task. In Experiment 1 stimuli were judged as being either in the same orientation or mirror-reversed, a task that does not require high-level semantic information to be processed. Experiment 2 required physically identical forms to be matched, which may use either physical or name information. In Experiment 1 "same" judgements were equivalent for both types of stimuli, and "different" judgements were longer for the "poorly" structured (non-nameable) forms. In Experiment 2 there was little overall difference between "well" and "poorly" structured forms, though response times to "well" structured (nameable) forms were slowed for right-visual-field presentations. It is suggested that familiarity may not be sufficient to provide a perceptual advantage for nameable forms, as the advantage for nameable stimuli was confined to "same" judgements in Experiment 1 and response times were shorter for non-nameable stimuli in Experiment 2. Rather, performance depends upon factors such as the computation of global shape (due to structural properties of collinearity and closure) and on the use of different kinds or representations (physical versus name) in matching.