Levels of coding in picture-picture comparison tasks

Two experiments are reported in which subjects had to match pairs of pictures of objects. "Same" pairs could be either identical (Ps), pictures of different views of the same object (Pv), or pictures of different objects having the same name (Pd). With line drawings as stimuli, RTs for Condition Ps were shorter than for Condition Pv, which in turn were shorter than for Condition Pd. Visual similarity had no effect on Pd RTs. However, in Experiment II, where photographs of objects with high-frequency (HF) and low-frequency (LF) names were used, no difference was found between Conditions Ps(HF), Ps(LF) and Condition Pv(HF); and no difference occurred between Conditions Pd(HF), Pd(LF) and Condition Pv(LF), the latter set of conditions being associated with longer RTs than the former. This pattern of results was found with both a .25-sec and a 2-sec ISI. The results are discussed in terms of the levels of coding involved in processing information from picture stimuli. It is concluded that at least two levels are involved in matching photographs of real objects (an object-code level and a nonvisual semantic code level), while a third level may be used in matching tasks involving stylized line drawings (a picture-code level).