Combining image degradations in a recognition task.

Six experiments are reported that investigate the effect on form recognition performance of combining three kinds of stimulus degradations: local area averaging of intensities, low-pass spatial frequency filtering, and random dot visual interference. The effects are shown to be more complicated than previously reported in simple demonstrations. The complexity of the results suggests that models based on single stimulus attributes such as energy or spatial frequency spectrum probably cannot account for the data. Eclectic theories that invoke combinations of redundant processes may be necessary for describing visual recognition phenomena, even within the limited domain examined in this study.