Figure 1.
Example of areas of interest (AOIs).
For each face stimulus, we defined AOIs: the eyes, nose, and mouth. In order to control for differences in sizes of AOIs, the fixation duration and fixation frequency were normalized by the AOI (relative fixation duration and relative fixation frequency) so that the sum of fixation duration and that of fixation frequency would be 1 for each trial.
Figure 2.
Mean rating scores of emotional valence as a function of expression in face stimuli.
The face stimuli with happy expressions (HO and HC) were evaluated positively while the face stimuli with sad (SD), angry (AO and AC), disgust (DI), and contempt (CT) expressions were rated negatively. The faces with neutral (NE) and surprised (SP) expressions were evaluated neither positively nor negatively. NE = neutral; HO = happiness with the mouth opened; FE = fear, AC = anger with the mouth closed; CT = contempt; DI = disgust; SD = sadness; HC = happiness with the mouth closed; AO = anger with the mouth opened; and SP = surprise.
Figure 3.
Total fixation duration mapped onto an example face image: (a) deaf participants, (b) hearing participants, (c) female participants, and (d) male participants.
Red regions represent the places where the participants' eyes stayed longer. The fixation patters differed among the participant groups.
Figure 4.
(a) Relative fixation duration as a function of area of interest averaged over all facial expressions within different combinations of participant groups. Participants tended to fixate on the eyes and nose longer than on the mouth. (b) Relative fixation duration compared between deaf and hearing participants. The deaf participants looked at the eyes longer than the nose whereas the hearing participants gazed at the nose longer than the eyes. (c) Relative fixation duration compared between female and male participants. The female participants tended to fixate on the eyes longer than did the male participants.
Figure 5.
Relative fixation duration for the different areas of interest as a function of facial expression, averaged over all the participants.
The faces with neutral expression led to longer fixation duration on the eyes. NE = neutral; HO = happiness with the mouth opened; FE = fear, AC = anger with the mouth closed; CT = contempt; DI = disgust; SD = sadness; HC = happiness with the mouth closed; AO = anger with the mouth opened; and SP = surprise.
Figure 6.
(a) Relative fixation frequency as a function of area of interest averaged over all facial expressions within different combinations of participant groups. (b) Relative fixation frequency compared between deaf and hearing participants. (c) Relative fixation frequency compared between female and male participants. The results for fixation frequency corroborated those of fixation duration.
Figure 7.
Relative fixation frequency for the different areas of interest as a function of facial expression averaged over all the participants.
The results for fixation frequency corroborated those of fixation duration. NE = neutral; HO = happiness with the mouth opened; FE = fear, AC = anger with the mouth closed; CT = contempt; DI = disgust; SD = sadness; HC = happiness with the mouth closed; AO = anger with the mouth opened; and SP = surprise.