Learned trustworthiness and face trustworthiness do not have the same influence on implicit responses to faces measured via fast periodic visual stimulation (FPVS)

Although people readily form impressions based on facial appearance, they also form impressions based on other sources of information, such as information about a person’s past actions. Past research has demonstrated that it is possible to detect implicit responses to face trustworthiness using fast periodic visual stimulation (FPVS) in conjunction with electroencephalography (EEG). Because people readily retrieve affective associations with faces, the current study investigated whether learned trustworthiness would yield similar responses to face trustworthiness as measured via FPVS. In support of this possibility, FPVS has been found to be sensitive to both face familiarity and to semantic categorization. Over the course of a week, participants learned to associate faces with negative or positive behaviors. Later, while EEG was recorded, participants completed three separate FPVS tasks. In each of these tasks, participants viewed oddball sequences of faces where a single base face was presented repeatedly at a rate of 6 Hz and oddball faces with different identities were presented every fifth face (6 Hz/5 = 1.2 Hz). Reproducing and extending prior findings, we observed a robust response at 1.2 Hz and its harmonics to faces with learned associations as compared to novel faces over right occipitotemporal cortex, as well as over a number of other electrode sites, including fronto-central sites. In addition, also reproducing earlier findings, we observed a stronger response at 1.2 Hz and its harmonics for sequences with less trustworthy-looking versus trustworthy-looking oddball faces over right occipitotemporal cortex and a number of other sites. However, contrary to our predictions, we did not observe a significant influence of learned trustworthiness on the oddball response. These data indicate that impressions based on learning are treated differently than impressions based on appearance, and they raise questions about the types of design and stimuli that yield responses that are measurable via FPVS.