Detection and identification of spatial frequency: models and data.

Detection and identification of up to four simple sinusoidal gratings were studied. The experimental results were quantitatively compared to predictions from several models. The models all assumed probabilistically independent channels sensitive to different ranges of spatial frequency. The models differed in the shapes of their underlying distributions and, for detection, their decision rule. Detection and identification of far-apart spatial frequencies were consistent with these models. Thus, uncertainty effects for both detection and identification (the decrease in performance with an increase in the number of possible spatial frequencies) can be explained without assuming that attention capacity is limited.