Fixation-pattern similarity analysis reveals adaptive changes in face-viewing strategies following aversive learning

Abstract

Animals can effortlessly adapt their behavior by generalizing from past aversive experiences, allowing to avoid harm in novel situations. We studied how visual information was sampled by eye-movements during this process called fear generalization, using faces organized along a circular two-dimensional perceptual continuum. During learning, one face was conditioned to predict a harmful event, whereas the most dissimilar face stayed neutral. This introduced an adversity gradient along one specific dimension, while the other, unspecific dimension was defined solely by perceptual similarity. Aversive learning changed scanning patterns selectively along the adversity-related dimension, but not the orthogonal dimension. This effect was mainly located within the eye region of faces. Our results provide evidence for adaptive changes in viewing strategies of faces following aversive learning. This is compatible with the view that these changes serve to sample information in a way that allows discriminating between safe and adverse for a better threat prediction.

Neural signature of delayed fear generalization under stress

“…The previous studies that tested fear generalization immediately after acquisition and to which we compare the present findings, included 29 participants (Onat & Büchel, 2015) and 74 participants (Kampermann et al, 2019), respectively. In these studies, participants were also young, healthy individuals and largely the same inclusion and exclusion criteria were applied.…”

“…Face stimuli were shown for 1.5 s and, in shocked trials, the US was presented after 1.4 s and co-terminated with face offset. The mean inter-trial interval (ITI) was 3.5 s, ranging between 1.5 and 5.5 s. The ITI was slightly different (3.5 s vs. ~4 s) to the previous studies (Kampermann et al, 2019;Onat & Büchel, 2015). During the baseline phase, the complete set of faces was shown, to control for any a priori differences between the faces.…”

“…Although our study was mainly designed to assess stress effects on (delayed) fear generalization, we also aimed to investigate time-dependent changes in fear generalization and its neural basis. To this end, we contrasted our findings with those of two previous studies that used the same experimental paradigm but without a delay between fear acquisition and generalization test (Kampermann et al, 2019;Onat & Büchel, 2015). We hypothesized that fear generalization would be increased after a 24-hr delay, relative to when tested immediately after acquisition.…”

“…In order to assess fear generalization processes, we used a recently introduced paradigm (Onat & Büchel, 2015). If not specified otherwise, the procedure was exactly the same as in the previous studies (Kampermann et al, 2019;Onat & Büchel, 2015). This paradigm included eight face stimuli arranged on a circular similarity continuum with two axes (x-axis: identity; y-axis: gender; Figure 1a).…”

“…stimuli most similar to the CS+ (|GS45|) and created a difference variable by subtracting this mean response from the CS+. In addition, we re-analyzed the behavioral results of two previous studies using the exact same paradigm in which the test phase was presented immediately after the fear acquisition phase (Kampermann et al, 2019;Onat & Büchel, 2015) and compared those results to ours.…”