Biology subjects

Pegna, A. J.

Publications and source records attributed to Pegna, A. J..

5 recordsLinked to original sources

bioRxiv2023

Faces capture spatial attention only when we want them to: an inattentional blindness EEG study

Previous research on emotional face processing has shown that emotional faces such as fearful faces may be processed without visual awareness. However, evidence for nonconscious attention capture by fearful faces is limited. In fact, studies using sensory manipulation of awareness (e.g., backward masking paradigms) have shown that fearful faces do not attract attention during subliminal viewings nor when they were task-irrelevant. Here, we used a three-phase inattentional blindness paradigm and electroencephalography to examine whether faces (fearful and neutral) capture attention under different conditions of awareness and task-relevancy. We found that the electrophysiological marker for attention capture, the N2-posterior-contralateral (N2pc), was elicited by face stimuli only when participants were aware of the faces and when they were task-relevant (phase 3). When participants were unaware of the presence of faces (phase 1) or when the faces were irrelevant to the task (phase 2), no N2pc was observed. Together with our previous work, we concluded that fearful faces, or faces in general, do not attract attention unless we want them to.

neuroscience↗

bioRxiv2023

Attentional capture by fearful faces requires consciousness and is modulated by task-relevancy: a dot-probe EEG study

In the current EEG study, we used a dot-probe task in conjunction with backward masking to examine the neural activity underlying awareness and spatial processing of fearful faces and the neural processes for subsequent cued spatial targets. We presented face images under different viewing conditions (subliminal and supraliminal) and manipulated the relation between a fearful face in the pair and a subsequent target. Through both mass univariate analysis and multivariate pattern analysis, we found that fearful faces can be processed to an extent where they attract spatial attention only when they are presented supraliminally and when they are task-relevant. The spatial attention capture by fearful faces also modulated the processing of subsequent lateralised targets that were spatially congruent with the fearful face, in both behavioural and neural data. There was no evidence for nonconscious processing of the fearful faces in the current paradigm. We conclude that spatial attentional capture by fearful faces requires visual awareness and it is modulated by top-down task demands.

neuroscience↗

bioRxiv2022

Decoding Neural Patterns for the Processing of Fearful Faces under Different Visual Awareness Conditions: A Multivariate Pattern Analysis

Mixed findings have been reported for the nonconscious processing of fearful faces. Here, we used multivariate pattern analysis on electroencephalography data from three backward masking experiments to decode the conscious and nonconscious processing of fearful faces. Three groups of participants were shown pairs of faces that were presented either subliminally (16 ms) or supraliminally (266 ms) and were required to complete tasks where the face stimuli were either task-relevant (Experiment 1) or task-irrelevant (Experiments 2 and 3). We decoded the neural activity to examine the temporal dynamics of visual awareness, and to investigate whether the presence and location of a fearful face were processed when levels of awareness varied. The results reveal that the spatial location of fearful faces can be decoded from neural patterns only when they are consciously seen and relevant to participants task. Nevertheless, the processing of the mere presence of fearful faces can occur in the absence of visual awareness, and the related neural patterns can be generalised to the conscious, non-spatial processing of fearful faces. Additionally, the flexibility of spatial attention seems to modulate the processing of fearful faces.

neuroscience↗

bioRxiv2022

Now you see it: fixation-related electrical potentials during a free visual search task reveal the timing of visual awareness

It has been repeatedly claimed that emotional faces capture attention readily, and that they are processed without awareness. Yet some observations cast doubt on these assertions. Part of the problem may lie in the experimental paradigms employed. Here, we used a free viewing visual search task and simultaneously recorded electroencephalography and eye-movements. Fixation-related potentials were computed for fearful and neutral facial expressions, and the electrical response compared when participants were aware or unaware of the fixated stimulus. We showed that the P300 increased across repeated fixations on the unseen targets, culminating in a conscious report, likely reflecting evidence accumulation. Awareness of the stimulus was associated with electrical changes emerging at around 130 ms, with emotions of the stimulus being dissociated only after awareness had arisen. These results suggest that the earliest electrical correlate of awareness emerges at around 130 ms in visual search and that emotion processing requires visual awareness.

neuroscience↗

bioRxiv2020

Attention and prediction modulations in expected and unexpected visuospatial trajectories.

Humans are constantly exposed to a rich tapestry of visual information in a potentially changing environment. To cope with the computational burden this engenders, our perceptual system must use prior context to simultaneously prioritise stimuli of importance and suppress irrelevant surroundings. This study investigated the influence of prediction and attention in visual perception by investigating event-related potentials (ERPs) often associated with these processes, N170 and N2pc for prediction and attention, respectively. A contextual trajectory paradigm was used which violated visual predictions and neglected to predetermine areas of spatial interest, to account for the potentially unpredictable nature of a real-life visual scene. Participants (N=36) viewed a visual display of cued and non-cued shapes rotating in a five-step predictable trajectory, with the fifth and final position of either the cued or non-cued shape occurring in a predictable or unpredictable spatial location. To investigate the predictive coding theory of attention we used factors of attention and prediction, whereby attention was manipulated as either cued or non-cued conditions, and prediction manipulated in either predictable or unpredictable conditions. Results showed both enhanced N170 and N2pc amplitudes to unpredictable compared to predictable stimuli. Stimulus cueing status also increased N170 amplitude, but this did not interact with stimulus predictability. The N2pc amplitude was not affected by stimulus cueing status. In accordance with previous research these results suggest the N170 is in part a visual prediction error response with respect to higher-level visual processes, and furthermore the N2pc may index attention reorientation. The results demonstrate prior context influences the sensitivity of the N170 and N2pc electrophysiological responses. These findings add further support to the role of N170 as a prediction error signal and suggest that the N2pc may reflect attentional reorientation in response to unpredicted stimulus locations.

neuroscience↗