The Cone of Direct Gaze: A Stable Trait

Abstract

Direct eye gaze is a potent stimulus in social interactions and is often associated with interest and approach orientation. Yet, there is remarkable variability in the range of gaze lines that people accept as being direct. A measure that is frequently used to quantify the range of gaze angles within which an observer assumes mutual gaze is the cone of direct gaze (CoDG). While individual differences in CoDG have often been examined, studies that systematically investigate the stability of an observers' CoDG over time are scarce. In two experiments, we measured the CoDG using an established paradigm and repeated the measurement after 5 min and/or after 1 week. We found high inter-individual variation, but high agreement within participants (ICCs between 0.649 and 0.855). We conclude that the CoDG can be seen as a rather stable measure, much like a personality trait.

Keywords: Bland–Altman plot; CoDG; cone of gaze; direct gaze; individual differences; stability.

Figure 1

Stimulus examples in three different viewing angles (A) and schematic time line of the gaze discrimination task (B). The task consisted of a variable inter-stimulus interval (ITI), followed by a stimulus face (300 ms), which was then replaced with a response window (1,700 ms). Participants responded whether or not the stimulus face was looking at them via two orthogonally arranged custom-made response buttons.

Figure 2

Individual CoDG in angular degrees, separately for baseline, after 5 min, and after 1 week. The bold line depicts the mean CoDG.

Figure 3

Bland–Altman plots for comparisons between baseline and after 5 min (A), between baseline and after 1 week (B), and between sessions after 5 min and 1 week (C). Red lines depict 95% CI, blue line depicts grand mean. The Y-axis of the Bland–Altman plot represents the difference between paired measurements (intra-individual variation) while the X-axis represents the mean of the paired measurements (inter-individual variation).

Figure 4

Individual CoDG in angular degrees, separately for baseline, and after 1 week. The bold line depicts the mean CoDG.

Figure 5

Bland–Altman plots for comparison between baseline and after 1 week. Red lines depict 95% CI, blue line depicts grand mean. The Y-axis of the Bland–Altman plot represents the difference between paired measurements (intra-individual variation) while the X-axis represents the mean of the paired measurements (inter-individual variation).