Modelling spatial recall, mental imagery and neglect

We present a computational model of the neural mechanisms in the pari-etal and temporal lobes that support spatial navigation, recall of scenes and imagery of the products of recall. Long term representations are stored in the hippocampus, and are associated with local spatial and object-related features in the parahippocampal region. Viewer-centered representations are dynamically generated from long term memory in the parietal part of the model. The model thereby simulates recall and im-agery of locations and objects in complex environments. After parietal damage, the model exhibits hemispatial neglect in mental imagery that rotates with the imagined perspective of the observer, as in the famous Milan Square experiment [1]. Our model makes novel predictions for the neural representations in the parahippocampal and parietal regions and for behavior in healthy volunteers and neuropsychological patients.

Differences between Spatial and Visual Mental Representations

This article investigates the relationship between visual mental representations and spatial mental representations in human visuo-spatial processing. By comparing two common theories of visuo-spatial processing – mental model theory and the theory of mental imagery – we identified two open questions: (1) which representations are modality-specific, and (2) what is the role of the two representations in reasoning. Two experiments examining eye movements and preferences for under-specified problems were conducted to investigate these questions. We found that significant spontaneous eye movements along the processed spatial relations occurred only when a visual mental representation is employed, but not with a spatial mental representation. Furthermore, the preferences for the answers of the under-specified problems differed between the two mental representations. The results challenge assumptions made by mental model theory and the theory of mental imagery

A computational theory of visuo-spatial mental imagery

The thesis develops a new theory of visuo-spatial mental imagery: the perceptual instantiation theory. The theory is concretized in a formal framework and implemented as a computational model. The theory and its model are evaluated against a set of empirical phenomena and compared to the contemporary theories of mental imagery. The new theory is shown to provide explanations for the considered phenomena that partly go beyond those of the contemporary theories

Predicting mental imagery based BCI performance from personality, cognitive profile and neurophysiological patterns

Mental-Imagery based Brain-Computer Interfaces (MI-BCIs) allow their users to send commands to a computer using their brain-activity alone (typically measured by ElectroEncephaloGraphy— EEG), which is processed while they perform specific mental tasks. While very promising, MI-BCIs remain barely used outside laboratories because of the difficulty encountered by users to control them. Indeed, although some users obtain good control performances after training, a substantial proportion remains unable to reliably control an MI-BCI. This huge variability in user-performance led the community to look for predictors of MI-BCI control ability. However, these predictors were only explored for motor-imagery based BCIs, and mostly for a single training session per subject. In this study, 18 participants were instructed to learn to control an EEG-based MI-BCI by performing 3 MI-tasks, 2 of which were non-motor tasks, across 6 training sessions, on 6 different days. Relationships between the participants’ BCI control performances and their personality, cognitive profile and neurophysiological markers were explored. While no relevant relationships with neurophysiological markers were found, strong correlations between MI-BCI performances and mental-rotation scores (reflecting spatial abilities) were revealed. Also, a predictive model of MI-BCI performance based on psychometric questionnaire scores was proposed. A leave-one-subject-out cross validation process revealed the stability and reliability of this model: it enabled to predict participants’ performance with a mean error of less than 3 points. This study determined how users’ profiles impact their MI-BCI control ability and thus clears the way for designing novel MI-BCI training protocols, adapted to the profile of each user

The role of mental imagery in creativity

Mental imagery has been linked to creativity through the reports of many historically creative individuals. Following a review and evaluation of the theoretical, anecdotal and empirical literature, the material presented in the thesis investigates the role of individual differences in mental imagery in performance on psychometric creativity tasks. A meta-analytic review of previous research showed a small marginally acceptable criterion association between self-reported mental imagery vividness and control and divergent thinking performance. However, additional non-statistical examination showed that further investigation was required. This led to five studies of the variables under consideration and a revised meta-analytic review in the light of the findings. The main conclusion was that self-report measures of mental imagery have a statistically significant but inconsequential association with divergent thinking performance. Consequently a new series of studies was undertaken in which the creative visualization task (CVT) was employed using an individual differences approach. Having established the parametric properties of a test-format version of the CVT two behavioural measures of mental imagery were used to predict performance. As neither measure predicted CVT performance high and low vividness and Symbolic Equivalence Test groups were used to assess a dissociative model of CVT performance. A significant interaction effect showed that vividness plays a mediating role in predicting CVT performance. In two final studies the individual differences approach was employed in the context of a hypothesised perceptual mediation. The results showed firstly that High Imagers performed significantly better than Low Imagers in creativity tasks following perceptual isolation and secondly that Low Imagers performed significantly better on perceptually sourced creativity tasks than on verbally sourced creativity tasks. The combined findings suggest that, while established protocols do not support a strong imagery-creativity association, new methods of investigation may reveal the predicted differences in creativity between high and low imagery participants

Mental Imagery Rotation and Graph Comprehension of IS-LM Macroeconomic Models

The aim of this study was to determine if the ability to rotate mental imagery influenced the comprehension of graphs in economics. A sample of 140 Business Administration undergraduates familiar with economic analysis using graphs were administered the Measure of the Ability to Rotate Mental Images (MARMI). Moreover, participants completed an ad hoc graph comprehension test consisting of six exercises of increasing difficulty with graphs developing the IS-LM model described in conventional macroeconomic textbooks. Both the ability to rotate mental imagery and graph complexity (the number of quadrants in each graph) were found to significantly influence the number of correct graph comprehension responses