RESPONSE DEPENDENCY AND PROCESSING DEPENDENCY OF LINE ORIENTATION ANDPOSITION IN A SINGLE ITEM TASK

The relation between the processing of line-orientation information an d position information was studied in two single-item recognition expe riments with percentage correct as the dependent variable. In Experime nt 1 subjects had to name the position and the orientation of a small oriented line segment in an otherwise empty field. In Experiment 2 sub jects had to indicate in addition whether a line segment had been pres ented or not. Both experiments showed that orientation responses and p osition responses are highly and positively correlated. Inconsistencie s in the results of two equivalent signal-detection analyses in Experi ment 2 are interpreted as indicating that in the present type of task subjects often have no information about the target and have to guess. It is concluded that in such a situation a high-threshold model (subj ects respond correctly if adequate information is available, and other wise guess) is best suited to describe the results. After an appropria te correction for guessing, no orientation processing without position processing was found.