Conceptual penetration of visual processing

Abstract

In traditional hierarchical models of information processing, visual representations feed into conceptual systems, but conceptual categories do not exert an influence on visual processing. We provide evidence, across four experiments, that conceptual information can in fact penetrate early visual processing, rather than merely biasing the output of perceptual systems. Participants performed physical-identity judgments on visually equidistant pairs of letter stimuli that were either in the same conceptual category (Bb) or in different categories (Bp). In the case of nonidentical letters, response times were longer when the stimuli were from the same conceptual category, but only when the letters were presented sequentially. The differences in effect size between simultaneous and sequential trials rules out a decision-level account. An additional experiment using animal silhouettes replicated the major effects found with letters. Thus, performance on an explicitly visual task was influenced by conceptual categories. This effect depended on processing time, immediately preceding experience, and stimulus typicality, which suggests that it was produced by the direct influence of category knowledge on perception, rather than by a postperceptual decision bias.

Fig. 1

Experimental design for Experiments 1 through 3. The two letters on each trial were the same, physically different but from the same conceptual category, or physically different and from different conceptual categories. These letters were presented either simultaneously or sequentially. On the sequential trials, the first stimulus remained visible during a variable delay (stimulus onset asynchrony, or SOA) before onset of the second stimulus.

Fig. 2

Results from (a) Experiment 1 (upright letters) and (b) Experiment 2 (rotated letters). The graphs show mean reaction times on different trials as a function of stimulus onset asynchrony (SOA), separately for within-category and between-category trials. Error bars represent ±1 SE of the mean difference score for a given SOA.

Fig. 3

Mean reaction times on different trials in Experiment 3 as a function of stimulus onset asynchrony (SOA), separately for within-category and between-category trials. Error bars represent ±1 SE of the mean difference score for a given SOA.

Fig. 4

Probability density functions of participants in Experiments 1 and 3. Each point represents the normalized frequency of a peak category effect (reaction time for within-category trials minus reaction time for across-category trials) for a particular stimulus onset asynchrony (SOA).

Fig. 5

The stimuli used in Experiment 4 and the mean time to classify each as a “cat” or a “dog.” C1 and D1 served as “typical” stimuli. C3 and D3 served as “atypical” stimuli.

Fig. 6

Mean reaction times on different trials in Experiment 4 as a function of stimulus onset asynchrony (SOA), separately for within-category (cat_a-cat_b, dog_a-dog_b) and between-category (cat-dog) trials. Error bars represent ±1 SE of the mean difference score for a given SOA.