No âmbito do projeto de investigação 129/20 - Investigating the role of expertise in the predictive coding framework combining time resolved neural and behavioural evidence, apoiado pela Fundação BIAL, Marie Smith e colaboradores, através de uma tarefa de categorização comportamental em que 67 participantes aprenderam a associação probabilística entre uma cor e uma categoria visual de alta e baixa expertise (faces e carros, respetivamente), avaliaram o nível individual de expertise em cada categoria. Encontraram que a perceção da categoria de alta expertise (faces) foi modulada pela expectativa. Ou seja, houve uma resposta mais rápida quando as faces eram esperadas. Além disso, na análise da atividade neural (EEG), houve efeitos da expectativa, com descodificação significativa da resposta neural a estímulos esperados. Estes resultados apoiam a influência da expectativa na perceção de faces, destacam o papel da expertise e chamam a atenção para a variabilidade individual que, muitas vezes, é negligenciada. Mais informações disponíveis no artigo Effects of expectation on face perception and its association with expertise publicado na revista científica Scientific Reports.
ABSTRACT
Perceptual decisions are derived from the combination of priors and sensorial input. While priors are broadly understood to reflect experience/expertise developed over one’s lifetime, the role of perceptual expertise at the individual level has seldom been directly explored. Here, we manipulate probabilistic information associated with a high and low expertise category (faces and cars respectively), while assessing individual level of expertise with each category. 67 participants learned the probabilistic association between a colour cue and each target category (face/car) in a behavioural categorization task. Neural activity (EEG) was then recorded in a similar paradigm in the same participants featuring the previously learned contingencies without the explicit task. Behaviourally, perception of the higher expertise category (faces) was modulated by expectation. Specifically, we observed facilitatory and interference effects when targets were correctly or incorrectly expected, which were also associated with independently measured individual levels of face expertise. Multivariate pattern analysis of the EEG signal revealed clear effects of expectation from 100 ms post stimulus, with significant decoding of the neural response to expected vs. not stimuli, when viewing identical images. Latency of peak decoding when participants saw faces was directly associated with individual level facilitation effects in the behavioural task. The current results not only provide time sensitive evidence of expectation effects on early perception but highlight the role of higher-level expertise on forming priors.
