Eye tracking of attention in the affective disorders: a meta-analytic review and synthesis

Abstract

A large body of research has demonstrated that affective disorders are characterized by attentional biases for emotional stimuli. However, this research relies heavily on manual reaction time (RT) measures that cannot fully delineate the time course and components of attentional bias. Eye tracking technology, which allows relatively direct and continuous measurement of overt visual attention, may provide an important supplement to RT measures. This article reviews eye tracking research on anxiety and depression, evaluating the experimental paradigms and eye movement indicators used to study attentional biases. Also included is a meta-analysis of extant eye tracking research (33 experiments; N=1579) on both anxiety and depression. Relative to controls, anxious individuals showed increased vigilance for threat during free viewing and visual search, and showed difficulty disengaging from threat in visual search tasks, but not during free viewing. In contrast, depressed individuals were not characterized by vigilance for threat during free viewing, but were characterized by reduced orienting to positive stimuli, as well as reduced maintenance of gaze on positive stimuli and increased maintenance of gaze on dysphoric stimuli. Implications of these findings for theoretical accounts of attentional bias in anxiety and depression are discussed, and avenues for future research using eye-tracking technology are outlined.

Figure 1

An example of EM data and the eye tracking paradigms considered in the meta-analysis: (a) 3-s scan path in a free viewing task. Circles indicate fixations, diameter of circles indicates duration, and lines indicate saccade sequence. (b–c) Examples of ‘odd-one-out’ visual search task conditions: (b) threat-related target amidst neutral distractors, (c) neutral target amidst threat-related distractors. All facial expressions from the NimStim Face Stimulus Set (Tottenham et al., 2009).

Figure 2

Orienting bias for threatening stimuli. In this and all subsequent forest plots, symbol size for point estimates represents study precision. Diamond represents estimate of combined effect size; horizontal edges of diamond represent upper and lower limits of 95% confidence interval.

Figure 3

Orienting bias for pleasant stimuli.

Figure 4

Initial maintenance bias for threatening stimuli in anxious versus non-anxious individuals.

Figure 5

Extended viewing of emotional stimuli in depressed versus non-depressed individuals.

Figure 6

Detection of threat and distraction by threat during visual search in anxious versus non-anxious individuals. For detection effects, negative values reflect facilitated detection in anxious versus non-anxious individuals. For distraction effects, positive values reflect increased distraction in anxious versus non-anxious individuals.