Interactions between concentric form-from-structure and face perception revealed by visual masking but not adaptation

Abstract

Findings from diverse subfields of vision research suggest a potential link between high-level aspects of face perception and concentric form-from-structure perception. To explore this relationship, typical adults performed two adaptation experiments and two masking experiments to test whether concentric, but not nonconcentric, Glass patterns (a type of form-from-structure stimulus) utilize a processing mechanism shared by face perception. For the adaptation experiments, subjects were presented with an adaptor for 5 or 20 s, prior to discriminating a target. In the masking experiments, subjects saw a mask, then a target, and then a second mask. Measures of discriminability and bias were derived and repeated measures analysis of variance tested for pattern-specific masking and adaptation effects. Results from Experiment 1 show no Glass pattern-specific effect of adaptation to faces; results from Experiment 2 show concentric Glass pattern masking, but not adaptation, may impair upright/inverted face discrimination; results from Experiment 3 show concentric and radial Glass pattern masking impaired subsequent upright/inverted face discrimination more than translational Glass pattern masking; and results from Experiment 4 show concentric and radial Glass pattern masking impaired subsequent face gender discrimination more than translational Glass pattern masking. Taken together, these findings demonstrate interactions between concentric form-from-structure and face processing, suggesting a possible common processing pathway.

Keywords: Glass patterns; face perception; holistic processing; moire perception; visual adaptation; visual masking.

Figure 1

Radial (A), concentric (B), translational (C), and random (D) Glass patterns used in this study are depicted.

Figure 2

Examples of flower (A), inverted face (B), and upright face (C) adaptors used in Experiment 1 are shown here. The N-O mask (D) was used as a process-terminating backward mask in Experiment 2.

Figure 3

Schematic of Experiment 1 paradigm. An explanation of the schematic is provided in the text.

Figure 4

Discriminability is plotted for the 12 runs performed during the experiment. Each column represents runs where the pattern targets were of a particular type (radial, concentric, or translational). The solid line represents the expected performance for the participants in the absence of an adaptor as determined by the staircasing procedure. Each row represents the type of adaptor stimulus used in each block. Flower adaptation impaired radial Glass pattern discrimination (dotted black circle) relative to face and random adaptation (dotted black lines). Flower and face adaptation impaired translational Glass pattern discrimination relative to random adaptation (gray circles). The targets shown in the figure are enlarged to make the global forms visible; the actual size of the targets is described in the General methods section.

Figure 5

β estimates for Experiment 1 are plotted for the 12 runs in Experiment 1. The organization of the figure is the same as in the Figure 4. The solid line represents the β value where bias is neutral.

Figure 6

Schematic for the paradigm used in Experiment 2. Explanation of the schematic is provided in the text.

Figure 7

Examples of degraded faces are shown here. For Experiments 2 and 3, the median percentage of face pixels swapped for upright (A) and inverted (B) faces was 77%. For Experiment 4, the median percentage of face pixels swapped for male (C) and female (D) faces was 50%.

Figure 8

Measures of discriminability (top) and bias (bottom) for the conditions in Experiment 2. The no-adaptation condition (solid black) is compared with the noncontrol conditions (dotted black): (A) gap-absent/N–O-mask condition, (B) gap-absent/whole-faces condition, (C) gap-present/N–O-mask condition, (D) gap-present/noise-mask condition. For clarity, examples of target faces (left) and masks (right) in the adaptation conditions are shown above. These stimuli are not drawn to scale.

Figure 9

Schematic for the paradigm used in Experiments 3 and 4.

Figure 10

Examples of the relative location of the offset (light) and center (dark) faces for Experiments 3 and 4. The offsets were shifted to provide positional ambiguity for the eyes in the center face. (A) The top face is an inverted face shifted up from the middle; the middle face is an upright face; the bottom face is an inverted face shifted down from the middle. (B) The top face is an upright face shifted up from the middle; the middle face is an inverted face; the bottom face is an upright faces shifted down from the middle.

Figure 11

Discriminability (A) and bias measures (C) for Experiment 3 are plotted for targets located in the center. Discriminability (B) and bias measures (D) for targets located offset from the center are also plotted. Lines and bars represent concentric (dotted gray), radial (solid gray), and translational (solid black) maskers. A pattern-specific effect of visual masking was found such that concentric masks impaired discriminability more than radial masks, which impaired discriminability more than translational masks (black ellipsoid). The dotted line represents the expected face discrimination performance with random Glass pattern masks at the 66.6-ms SOA, as determined by the staircasing procedure.

Figure 12

Discriminability (A), and bias (B) measures plotted for Experiment 4. Lines and bars represent concentric (dotted gray), radial (solid gray), and translational (solid black) maskers. Pattern-specific masking effects were observed such that concentric masks reduced face discriminability more than radial masks, which reduced face discriminability more than translational masks (black ellipsoid). The dotted line represents the expected gender discrimination performance with random Glass pattern masks at the 66.6-ms SOA (A) and the β value where bias is neutral (B).