Psychophysiology of EMOTIONS
Nonconscious processing and its impact on emotion, attention, and physiological responses.
In this research area, I will highlight two projects in which I was involved: one supported by FCT and the other by Bial Foundation, both conducted with my colleague Francisco Esteves, and one with my former PhD student, Pedro Rosa.
Over the past four decades, laboratory research has investigated the impact of evolutionarily "relevant" stimuli (e.g., dangerous animals from our ancestors' era) and compared them with ontogenetically fear-relevant stimuli (i.e., stimuli that evoke fear due to societal influences such as guns) and irrelevant-fear stimuli. Food stimuli are also noteworthy for their historical significance in human life and in eating disorders, but less explored. Overall, past studies indicated that fear learning and defensive reactions might stem from evolutionary roots. Physiological responses such as skin conductance responses were a primary method for measuring fear reactions, revealing that it is more challenging to diminish fear responses to those "evolutionarily relevant" stimuli (e.g., snake) than to less relevant ones (e.g., flowers). Moreover, the resistance to extinction in conditioning studies has been shown to be less evident with ontogenetic stimuli like guns. Furthermore, associative learning without awareness is typically observed with biologically fear-relevant stimuli, rather than with those relevant due to societal reasons.
These projects aim to investigate the subliminal processing of fear-relevant stimuli and its impact on attention and physiological responses, as well as the emotional responses to stimuli such as food, examining both conscious and nonconscious responses. Both projects seek to expand our understanding of how different types of stimuli, both evolutionarily and societally relevant, affect human emotional and physiological responses, and employ subliminal presentation, including conditioning paradigms.
This project was conducted with Pedro Rosa (+ Francisco Esteves), whom I also add the privilege to (co)supervise in both his master's dissertation (entitled "Exposure to Subliminal Affective Images and Fear of Snakes: their influence on affective and physiological states", 2008) and in his Ph.D. thesis.
It focused on the effects of emotional subliminal processing on attentional orienting and psychophysiological responses using snakes as stimuli. These studies aimed to determine if snakes could be processed pre-attentively due to their evolutionary importance, leading to increased attention and stronger psychophysiological reactions. Using visual attention tasks with eye tracking and physiological measures, we found that subliminally presented fear-relevant stimuli affected attentional orienting and activated the peripheral and central nervous systems.
Psychophysiology of Emotions: Nonconscious learning
This project, led by Francisco Esteves and funded by the Bial Foundation, concentrated on food stimuli. It aimed to explore emotional responses to food-related stimuli under both conscious and subliminal conditions. The studies found that while food stimuli are processed similarly to other emotional visual materials under conscious conditions, the results differed when presented subliminally. Specifically, heart rate changes appeared to be influenced by participants' attitudes towards food and body shape. However, the overall findings indicated a lack of subliminal effects, which contrasts with the past studies assessing associative learning with biologically fear-relevant stimuli. The hypothesis that food stimuli would elicit similar effects in participants concerned with food and body shape was also not supported. Regardless of the conditioned stimulus (food picture or neutral picture) and participants' food anxieties, there were no differences in autonomic responses, measured by skin conductance, during the extinction phase. These findings suggest that food stimuli do not receive preferential cognitive processing and do not trigger a fear response, aligning more with data from studies using fear-irrelevant stimuli.
Beyond traditional clinical measurements for screening fears and phobias. IEEE Transactions on Instrumentation and Measurement, 64 (12), 3396-3404. LINK
Emotional Responses (verbal and psychophysiological) to pictures of food stimuli. Psicologia, XXIV (2), 89-111. LINK
Ver ou não ver, eis a questão: A relação entre atenção visual selectiva e emoção. In-Mind Português, 3 (1-4), 15-24. LINK