Seeing Objects as Faces Enhances Object Detection

Abstract

The face is a special visual stimulus. Both bottom-up processes for low-level facial features and top-down modulation by face expectations contribute to the advantages of face perception. However, it is hard to dissociate the top-down factors from the bottom-up processes, since facial stimuli mandatorily lead to face awareness. In the present study, using the face pareidolia phenomenon, we demonstrated that face awareness, namely seeing an object as a face, enhances object detection performance. In face pareidolia, some people see a visual stimulus, for example, three dots arranged in V shape, as a face, while others do not. This phenomenon allows us to investigate the effect of face awareness leaving the stimulus per se unchanged. Participants were asked to detect a face target or a triangle target. While target per se was identical between the two tasks, the detection sensitivity was higher when the participants recognized the target as a face. This was the case irrespective of the stimulus eccentricity or the vertical orientation of the stimulus. These results demonstrate that seeing an object as a face facilitates object detection via top-down modulation. The advantages of face perception are, therefore, at least partly, due to face awareness.

Keywords: Face perception; face awareness; face detection; face inversion effect; signal detection theory.

Figure 1.

Stimuli and procedure used in Experiment 1. (a) Targets (first row) and an example of noise (second row). The targets on the left and middle were used in the face task, while the targets on the middle and right were used in the triangle task. (b) A trial sequence.

Figure 2.

Average d′ in Experiment 1. Error bars indicate SEM.

Figure 3.

Average d′ in Experiment 2. Error bars indicate SEM.

Figure 4.

Average d′ in Experiment 3. Error bars indicate SEM.

Figure 5.

Stimuli used in Experiment 4.

Figure 6.

Average d′ for the diamond target in Experiment 4. Error bars indicate SEM.