Response dependency and processing dependency of line orientation and position in a single-item task

The relation between the processing of line-orientation information and position information was studied in two single-item recognition experiments with percentage correct as the dependent variable. In Experiment 1 subjects had to name the position and the orientation of a small oriented line segment in an otherwise empty field. In Experiment 2 subjects had to indicate in addition whether a line segment had been presented or not. Both experiments showed that orientation responses and position responses are highly and positively correlated. Inconsistencies in the results of two equivalent signal-detection analyses in Experiment 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 (subjects respond correctly if adequate information is available, and otherwise guess) is best suited to describe the results. After an appropriate correction for guessing, no orientation processing without position processing was found.