Think positive! Resolving human motion ambiguity in the presence of disease threat

ABSTRACT

Recently, approach-avoidance tendencies and visual perception biases have been increasingly studied using bistable point-light walkers (PLWs). Prior studies have found a facing-the-viewer bias when one is primed with general threat stimuli (e.g. angry faces), explained by the “error management theory”, as failing to detect a threat as approaching is riskier than the opposite. Importantly, no study has explored how disease threat – linked to the behavioural immune system – might affect this bias. This study aimed to explore whether disease-signalling cues can alter how we perceive the motion direction of ambiguous PLWs. Throughout 3 experiments, participants indicated the motion direction of a bistable PLW previously primed with a control or disease-signalling stimuli – that is, face with a surgical mask (Experiment 1), sickness sound (Experiment 2), or face with a disease cue (Experiment 3). Results showed that sickness cues do not significantly modulate the perception of approach-avoidance behaviours. However, a pattern emerged in Experiments 2 and 3, suggesting that sickness stimuli led to more facing away percepts. Unlike other types of threat, this implies that disease-related threat stimuli might trigger a distinct perceptual bias, indicating a preference to avoid a possible infection source. Nonetheless, this finding warrants future investigations.

KEYWORDS:

• Behavioural immune system
• perception
• bistable human motion
• point-light walkers
• approach-avoidance

Author contributions

Ana C. Magalhães: Conceptualisation, Methodology, Software, Investigation, Formal analysis, Writing Fábio Silva: Conceptualisation, Methodology, Software, Investigation, Formal analysis, Writing Inês Lameirinha: Conceptualisation, Methodology, Investigation Mariana Rodrigues: Methodology Sandra C. Soares: Conceptualisation, Methodology, Writing, Supervision.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Statements and declarations

We report how we determined our sample size, all data exclusions, manipulations, and measures in the study. All three experiments and respective analyses were pre-registered.

Pre-registrations and the data and analysis scripts that support the findings of this study are available in Open Science Framework through the following hyperlinks: https://osf.io/sdvcf/ (data and scripts), https://osf.io/4y596 (pre-registration for Exp 1), https://osf.io/ck4gt (pre-registration for Exp 2), and https://osf.io/bn9hx (pre-registration for Exp 3).

We would like to express our sincere gratitude to the anonymous reviewers and associate editor whose valuable feedback and guidance significantly improved the quality of this paper.

Notes

1 Exclusion criteria were based on the possibility of distorted sensory perception, cognitive functioning, or overall health status, which could have introduced confounding variables in the data. Age and language criteria were also considered to account for potential cultural factors. Our decision was primarily based on the fact that the BIS has been found to be influenced by cultural and health-related issues (Miller & Maner, 2011; Murray & Schaller, 2016).

2 Data for all three experiments were collected between 2021 and 2022.

3 As this was not the primary goal of our study, the correlational analyses for all three experiments only focused on a subset of questionnaires selected for their established relevance to the BIS.

Additional information

Funding

This work was supported by the Portuguese Foundation for Science and Technology through Doctoral Fellowships awarded to ACM [grant numbers SFRH/BD/137993/2018 and COVID/BD/153435/2023] and FS [grant number SFRH/BD/145911/2019], and multiannual funding to the William James Center for Research [grant number UIDB/04810/2020]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.