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Human faces convey essential information for social behaviour, such as information about others’ mental states and intentions. Crucially, many studies have claimed that several facial features such as configural facial information, emotional expressions, and gaze direction modulate how faces gain access to perceptual awareness. However, the procedures employed in said studies suffer from multiple methodological issues and limitations. In a series of experiments, I tested whether configural facial features, emotional expressions, and gaze direction modulate how faces gain access to awareness. To achieve this, I used stringent procedures that allow measurement of perceptual sensitivity and decision criterion to the location and identity of faces. I used these measures to assess how long it takes faces to reach awareness as they overcome Continuous Flash Suppression – an interocular suppression technique that can render images invisible for several seconds. Using classical and Bayesian analyses, I found that configural face processing (which occurs for upright, but not inverted faces) promotes faces’ access to awareness. Similarly, faces making eye contact gain access to awareness faster than faces looking away. Contrary to past claims, however, I found that faces expressing negative emotional expressions (anger or fear) do not enter awareness faster than neutral expressions. In another series of experiments, I measured the minimal exposure durations required for configural facial processing, emotion processing, metacognition, and conscious access. To this end, I used a newly developed LCD tachistoscope that can present images with sub-millisecond precision and examined both behavioural (psychophysical) and neural (electroencephalography) markers of processing. I found that configural face processing promotes faces’ access to awareness by showing that upright faces require shorter exposure durations than inverted faces to be seen. Crucially, only around four milliseconds of exposure were required to find this advantage. Fearful expressions, however, do not gain access to awareness faster than neutral expressions. Evidence from neural markers expanded this by showing that the exposure duration required for configural facial processing is the same as that required for faces to reach conscious access. Finally, around six milliseconds of exposure were required for emotion processing. Together, these findings shed light on the factors that affect access of faces to awareness: configural facial information and gaze direction can modulate faces’ access to perceptual awareness; and such modulation is due to perceptual sensitivity rather than decision criterion. Furthermore, the perceptual processing of faces follows a hierarchical pattern: configural information precedes and facilitates access to awareness, and emotion processing follows awareness.

Working Memory can be conceived as a mental workspace holding and manipulating a limited amount of recently acquired information for a limited time. Some theories assume that it is tightly coupled with Consciousness (e.g., Baars & Franklin, 2003), commonly defined in experimental studies as the ability to report the content of perception or of memory. Other theories posit that working memory includes cognitive processes of which participants are not conscious (e.g., Soto et al., 2011; Logie, 2016), and can be activated without conscious intention (Hassin et al., 2009). Here, I describe experimental work designed to investigate the possible implicit activation of working memory without awareness. Importantly, participants were not only unaware of the stimuli that might be held in working memory, but also unaware that such stimuli were being presented at all. They were asked to guess which one of four cards presented on the screen was the winning one; one card was subliminally primed before a retention interval (which could vary between 500, 1000, 2000 and 5000 ms). The winner, on each trial, was chosen from amongst four blue cards, one of which had been primed, without awareness, by a card of a different colour (red or green) using Continuous Flash Suppression or Backward Masking. Bayesian and classical analyses from nine experiments mostly support the null hypothesis, thus indicating that working memory was not engaged in performing this task. Two conceptual replications and four exact replications of the original study by Soto et al. (2011), also failed in reproducing the original results. In conclusion, this collection of fifteen experiments encompassing different manipulations shows the absence of non-conscious WM retention, questioning the generalisability of previous studies showing non-conscious WM.

Micro-affordance effects have been reported for several different components of the reach-to-grasp action during both on-line and off-line visual processing. The presence of such effects represents a strong demonstration of the close relationship between perception, action, and cognition. In this thesis 7 experiments are described, which investigate different aspects of that relationship, with particular attention on the nature of object representations. In 5 behavioural experiments as well as in 1 Transcranial Magnetic Stimulation (TMS) experiment a stimulus-response compatibility paradigm is employed to examine the presence of micro-affordance effects arising during language processing of object names. The power and precision component of the reach-to-grasp action is investigated in relation to the compatibility of an object for grasping with either a power or a precision grasp. Overall, the results of the experiments discussed in the present thesis suggest that: a) object representations activated during language processing of object names are able to potentiate actions arising from the component of the reach-to-grasp action under investigation; b) such representations might be more semantic or „propositional‟ than depictive in nature, therefore more related to stored semantic knowledge of the object and its associated actions than to its detailed visual properties; c) this semantic information about objects seems to be automatically translated into specific motor activity, even in the absence of any intention to act; d) finally, such semantic, non-visual motor potentiation seems to be rapid and relatively short lived.