Implicit responses to face trustworthiness measured with fast periodic visual stimulation

Abstract

People rapidly and spontaneously form trustworthiness impressions based on facial appearance. Studies using functional magnetic resonance imaging find that activity in the amygdala and other brain regions tracks with face trustworthiness, even when participants are not explicitly asked to judge face trustworthiness. The current study investigated whether it would be possible to detect implicit responses using another method: fast periodic visual stimulation (FPVS). While scalp electroencephalogram (EEG) was recorded, participants viewed sequences of faces in which a single base face was presented at a rate of 6 Hz and oddball faces with different identities were presented every fifth face (6 Hz/5 = 1.2 Hz). Within a given sequence, the oddball faces were all either less trustworthy-looking or trustworthy-looking. The base face either matched the oddball faces on trustworthiness or did not match, so that the experiment had a 2 (trustworthiness of oddball) × 2 (match between base/oddball faces) design. Although participants’ task was unrelated to the faces, the trustworthiness of the oddball faces had a strong influence on the response at 1.2 Hz and its harmonics. There was a stronger response for sequences with less trustworthy- versus trustworthy-looking oddball faces over bilateral occipitotemporal sites, medial occipital sites, and beyond. In contrast, the match in trustworthiness between the base face and the oddball faces had only a minimal effect. The effect of oddball type was observed after a short recording time, suggesting that FPVS offers an efficient means of capturing implicit neural responses to face trustworthiness.

Trustworthiness perception is mandatory: Task instructions do not modulate fast periodic visual stimulation trustworthiness responses

“…This result suggests that facial trustworthiness can be processed implicitly, without needing instructions to judge trustworthiness. Using a similar FPVS oddball face individuation paradigm, Verosky et al (2020) also found evidence of implicit trustworthiness processing. Together these results suggest that the FPVS oddball response can be used as an objective and reliable neural marker of trustworthiness processing.…”

“…All participants first completed the implicit size condition so that our comparison of task instructions benefitted from a within-participant design. In this initial block, we also aimed to replicate the recent finding that an FPVS signal can be found in response to faces changing in trustworthiness in the absence of explicit trust judgement instructions ( Swe et al, 2020 ; Verosky et al, 2020 ).…”

“…Converging behavioral, electrophysiological, and neuroimaging research has indicated that trustworthiness perception can occur implicitly, that is without needing explicit impression formation instructions ( Klapper, Dotsch, van Rooij, & Wigboldus, 2016 ; Winston, Strange, O'Doherty, & Dolan, 2002 ; Swe, Palermo, Gwinn, Rhodes, Neumann, Payart, & Sutherland, 2020 ; Verosky, Zoner, Marble, Sammon, & Babarinsa, 2020 ), although not all studies do find evidence for implicit trustworthiness perception ( Santos & Young, 2005 ). The fact that trustworthiness is perceived implicitly from faces is suggestive of mandatory processing of trust.…”

“…We set out to investigate whether trustworthiness processing is mandatory by taking advantage of the fast periodic visual stimulation (FPVS) technique, an advance in the field of electroencephalography (EEG). To investigate this question, we used the FPVS oddball technique, taken from two recent studies which have shown that trustworthiness can be processed implicitly ( Swe et al, 2020 ; Verosky et al, 2020 ). This FPVS oddball paradigm ( Rossion, 2014 ) involves sequentially presenting faces at a predetermined, base frequency (e.g., six faces per second, resulting in a base frequency of 6 Hz).…”

Understanding trait impressions from faces

“…Specifically, trait information can be extracted from faces quickly (Willis & Todorov, 2006), spontaneously (Klapper et al, 2016), unconsciously (Freeman et al, 2014; Getov et al, 2015) and attractiveness impressions, at least, may be mandatory (Ritchie et al, 2017). Recent electrophysiological studies using the fast periodic visual stimulation technique have also established that a neural signal can be found in response to changes in trustworthiness in rapidly presented face images, without requiring instructions to judge trustworthiness (Swe et al, 2020; Verosky et al, 2020). It has yet to be established whether face‐based impressions are automatic in the sense of being capacity‐free.…”