ACTIVATION OF MOTOR INFORMATION DURING MANIPULABLE OBJECT PERCEPTION

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The ecological approach of visual perception

In the second half of the 20th century, Gibson proposed an ecological approach to visual perception (Gibson, 1979, 1986) that today, constitutes the roots of enactive approaches of perception. His conception has inspired a substantial number of works. To cite some examples, one may consider works on human interaction with machines (Flach & Hancock, 1992; Gaver, 1991), on conception design (Dhami et al., 2004) and his approach has even been extended to auditory perception (Gaver, 1993). Without going into details, the main contribution of ecological approaches is to consider the interplay between organisms – especially humans – and the environment (Bronfenbrenner, 1979; Gibson, 1986).
The ecological approach of visual perception differs from its contemporaries by refuting the inference principle. The inference principle postulates that stimulations (e.g., light, wave) are passively received by sensory channels (e.g., eyes, ears) and undergo computational processes by the cognitive system to bring out percepts (i.e., perception as we experience it). In opposition to this conception, the ecological approach to visual perception postulates a direct perception of environmental information (Gibson, 1986), meaning that information is contained in the environment, fully present in the stimulation pattern (also called invariant properties) of sensory input and thus refuting the concept of mental representation (Baggs & Chemero, 2018). Furthermore, Gibson (1986) emphasized on the adaptative role of the action-perception relationship. Action-perception relationship is thought to be an adaptative function for the survival of the individual according to environmental constraints (Ho, 1991). For example, space and time dimensions are considered to be perceived at the individual scale, depending on individual own action capabilities (for space perception) and life events (for time perception). In this regard, perception is considered to be unique to each individual and inseparable from action, perception guiding action in the environment and action leading to modulation in what it is perceived. Gibson (1986) goes even further by suggesting that perception is not only serving action but is an active phenomenon that emerges from action and from exploration of the environment.
The core element of Gibson’s approach (Gibson, 1979, 1986) is the term “affordance” that he coined to define information given by the environment to an organism. Affordances refer to action possibilities of an individual in the environment according to its own action capabilities. Along with perception, affordances are unique to each individual (Mark, 1987; Warren, 1984; Warren & Whang, 1987). They belong to objectivity and subjectivity, because they exist independently of perception but depend on individual’s action capabilities. For example, Warren (1984) showed that not all individuals perceive stairs of different heights as climbable, taller individuals judging higher stairs to be more climbable than smaller individuals. However, they found that the maximum stair height to be climbable was not higher than 88% of the leg length of each individual, suggesting that affordances depend on each individual but follow consistent rules across them. According to Gibson, affordances are therefore potential actions evoked by the environment – existing without being perceived – but their perception depends on the characteristics of the individual who perceives them.
To conclude, even though the ecological approach to visual perception is a contentious theory (Baggs & Chemero, 2018) – the absence of any cognitive/brain processing of sensorial information is largely debated – the theory has mainly contributed in focusing the conception of perception at the interplay between human beings and their environment, considering its strong interconnection with action. Furthermore, since Gibson has proposed the term “affordance” (1979, 1986), the term has been used in many different ways, especially for studying the perception of manipulable objects (Osiurak et al., 2017). The different conceptions of the term “affordance” will be discussed in chapter 2.

Neurophysiological approaches

From a neurophysiological point of view, it has been recently emphasized that perception and action are two systems that show no clear distinction, that is visual and action processing share several brain correlates. Most evidence comes from studies in monkeys, including ablation studies and single-cell recording. Discoveries were then extended to humans through direct and indirect evidence.

The two visual pathways

At the beginning of the 80’s, the discovery of two distinct cortical visual pathways in the monkey brain has provided substantive evidence for the existence of specific perceptual processing serving actions (Mishkin et al., 1983). The discovery was then extended to humans and refined through direct and indirect evidence. We will first discuss the discovery of the two visual pathways in monkeys and then, we will discuss evidence that extended the discovery to humans.

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Synthesis on neurophysiological approaches

Overall, the neurophysiological approaches suggest that both perception and action processing at the brain level are sometimes difficult to distinguish. Evidence from the literature on the two visual pathways and visuomotor neurons emphasized that perception and action share several brain correlates. In a sense, evidence in monkeys and generalization to humans suggest that we are phylogenetically and biologically organized for processing perception and action in a similar way. Additionally, we can consider both neurophysiological approaches as complementary aspects. The two-visual pathway framework describes the brain functioning for transforming visual to motor information at the level of neuron networks and the visuomotor neuron framework describing similar functions at the single-neuron level. Furthermore, when one approach emphasized the role of the parietal cortex in transforming object visual characteristics to motor properties (i.e., the two visual pathways), the other stressed the role of the premotor cortex in representing motor properties. Therefore, according to these discoveries, when one perceives graspable objects, it is natural to assume that its visual properties for action will be processed by the dorsal visual pathway (the “How” system), especially in the parietal cortex (i.e., anterior intraparietal cortex) and that, when specified, these properties will be transmitted to the premotor cortex. It is also legitimate to assume that in the premotor cortex, canonical neurons should be in charge of representing the selected action properties of the object. As an example, perceiving a mug will induce transformation of its visual features into action properties in the parietal cortex (e.g., matching of the mug size with the appropriate grasp aperture), and the specified action properties will be sent to the premotor cortex, allowing the perceiver to represent the typical actions associated with the mug.

Table of contents :

FIGURES
TABLES
BOXES
ABBREVIATIONS
INTRODUCTION
CHAPTER 1. PERCEPTION IS FOR ACTION
I. The ecological approach of visual perception
II. Neurophysiological approaches
1. The two visual pathways
2. Visuomotor neurons (canonical and mirror neurons)
Synthesis on neurophysiological approaches
III. Grounded cognition approaches
1. The multiple grounded accounts
2. Two illustrations of grounded cognition approaches
Synthesis on grounded cognition approaches
Global synthesis
CHAPTER 2. ACTIVATION OF MOTOR INFORMATION DURING MANIPULABLE OBJECT PERCEPTION
I. Automaticity, representation and brain processing
1. Micro-affordance account
2. Structural and functional affordances: Two Action Systems (2AS)
3. Stable and variable affordances
Intermediate synthesis
II. Affordance evocation during manipulable object perception
1. Initial claim about the automaticity of affordance evocation
2. Impact of context on the evocation of object affordances
Intermediate synthesis
Global Synthesis
CHAPTER 3. CONSEQUENCES OF THE CO-ACTIVATION OF MULTIPLE AFFORDANCES 
I. The affordance competition hypothesis
II. Behavioral assessments of the co-activation of affordances
1. Impact of the co-activation of distinct affordances on action production
2. Impact of the co-activation of affordances on object perception
Intermediate synthesis
III. Neurophysiological assessments of the co-activation of affordances
1. Involvement of distinct neurocognitive mechanisms in affordance selection
2. Mu (μ) rhythm desynchronization as a marker of affordance selection
Global synthesis
GOALS OF THE PRESENT THESIS
EXPERIMENTAL CONTRIBUTION
CHAPTER 4. MULTIPLE PARADIGMS ASSESSING AFFORDANCES: WHICH ONE SHOULD WE CHOOSE?
Section 1. Pilot study for selecting a paradigm assessing affordance evocation phenomenon
Section 2. Do manufactured and natural objects evoke similar motor information? The case of action priming.
Introduction
Method
Results
Discussion
Global synthesis
CHAPTER 5 DEVELOPMENTAL MODULATIONS OF THE COMPETITION BETWEEN AFFORDANCES DURING OBJECT PERCEPTION
Section 1. How competition between affordances affects object perception during development
Introduction
Method
Results
Discussion
Section 2. Complementary experiment. Does the visual complexity explain the affordance conflict cost?
Introduction
Method
Data analysis and results
Discussion
Global synthesis
CHAPTER 6. CONTEXTUAL MODULATION OF NEURAL MECHANISMS UNDERLYING COMPETITION BETWEEN AFFORDANCES DURING OBJECT PERCEPTION
Introduction
Method
Results
Discussion
Global synthesis
GENERAL DISCUSSION
Overall summary
I. Similarities and inconsistencies in the present thesis results
1. The role of manipulable object category in action priming
2. The role of object visual complexity in affordance conflict cost
3. The role of contextual modulations in affordance evocation
Global synthesis
II. Consequences on theories and models of affordance perception and action selection
1. How motor information of manipulable objects is represented at the cognitive level?
2. Inter- and intra-individual modulations of affordance evocation during manipulable object perception
3. What computational modeling has to offer?
III. Global conclusion
REFERENCES 

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