Perception and action in children with unilateral cerebral palsy

Perception and action are intertwined since action is a means to acquire perceptions (of space for example), and it is from perception that we are able to act on our environment. Children with cerebral palsy (CP) were born with reduced action capacity. Hence, with the first objective of this thesis we evaluated the effect of this action reduction on space perception in healthy and CP children. We showed that action reduction induced global and/or lateralized space perception deficits. Moreover, as a second aim, we improved action in healthy and CP children using action observation as motor priming. Therefore, this thesis highlighted the link between perception and action in healthy and CP children, in particular concerning action priming and space perception. Finally, we innovated in matter of diagnosis and rehabilitation for children with CP, in particular using robotic tools.(PSYE - Sciences psychologiques et de l'éducation) -- UCL, 201

Spatial biases in mental arithmetic are independent of reading/writing habits: Evidence from French and Arabic speakers.

The representation of numbers in human adults is linked to space. In Western cultures, small and large numbers are associated respectively with the left and right sides of space. An influential framework attributes the emergence of these spatial-numerical associations (SNAs) to cultural factors such as the direction of reading and writing, because SNAs were found to be reduced or inverted in right-to-left readers/writers (e.g., Arabic, Farsi, or Hebrew speakers). However, recent cross-cultural and animal studies cast doubt on the determining role of reading and writing directions on SNAs. In this study, we assessed this role in mental arithmetic, which requires explicit number manipulations and has revealed robust leftward or rightward biases in Western participants. We used a temporal order judgement task in French and Arabic speakers, two languages that have opposite reading/writing directions. Participants had to solve subtraction and addition problems presented auditorily while at the same time determining which of a left or right visual target appeared first on a screen. The results showed that the right target was favoured more often when solving additions than when solving subtractions both in the French- (n = 31) and Arabic-speaking (n = 25) groups. This was true even in Arabic-speaking participants whose preference for ordering of various series of numerical and non-numerical stimuli went from right to left (n = 10). These results indicate that SNAs in mental arithmetic cannot be explained by the direction of reading/writing habits and call for a reconsideration of current models to acknowledge the pervasive role of biological factors in SNAs in adults

Spatial biases in mental arithmetic are independent of reading/writing habits: Evidence from French and Arabic speakers

The representation of numbers in human adults is linked to space. In Western cultures, small and large numbers are associated respectively with the left and right sides of space. An influential framework attributes the emergence of these spatial-numerical associations (SNAs) to cultural factors such as the direction of reading and writing, because SNAs were found to be reduced or inverted in right-to-left readers/writers (e.g., Arabic, Farsi, or Hebrew speakers). However, recent cross-cultural and animal studies cast doubt on the determining role of reading and writing directions on SNAs. In this study, we assessed this role in mental arithmetic, which requires explicit number manipulations and has revealed robust leftward or rightward biases in Western participants. We used a temporal order judgement task in French and Arabic speakers, two languages that have opposing reading/writing directions. Participants had to solve subtraction and addition problems presented auditorily while at the same time determining which of a left or right visual target appeared first on a screen. The results showed that the right target was favoured more often when solving additions than when solving subtractions both in the French- (n=31) and Arabic-speaking (n=25) groups. This was true even in Arabic-speaking participants whose preference for ordering of various series of numerical and non-numerical stimuli went from right to left (n=10). These results indicate that SNAs in mental arithmetic cannot be explained by the direction of reading/writing habits and call for a reconsideration of current models to acknowledge the pervasive role of biological factors in SNAs in adults

Robot diagnosis test for egocentric and allocentric hemineglect

Objective: Patients with hemineglect fail to respond to egocentric stimuli or allocentric parts of stimuli contralateral to the brain lesion. The clinical diagnosis of hemineglect mainly involves evaluation of the egocentric form, while less sensitive standardized tests exist for other forms. Our global aim is to develop an innovative integrative robot measure, the MonAmour test, combining the assessment of egocentric, allocentric and motor hemineglect. Here, we present the egocentric and allocentric evaluations. Methods: Thirty-five first stroke patients (25 hemineglect) and 56 age-matched healthy controls were assessed on the index test (MonAmour) and on three reference standard tests (Bells test, Apples test and Neglect subtest of the Test for Attentional Performance). Based on controls' performance, normative data were created. Validity was evaluated between the MonAmour and the reference standard tests through correlations and test sensitivity/specificity. Reliability of the MonAmour was measured with test-retest and minimal detectable change. Results: Results demonstrated moderate to strong correlations between the MonAmour and the reference standard tests (r = .40-.88, p < .001 - p = .016). The sensitivity was high (50%-96%), with accurate diagnosis of patients with hemineglect, and reliability was excellent (Intraclass Correlation Coefficient = .79-.95, p < .001). Conclusions: The MonAmour robot test is a valid, sensitive and reliable tool that can diagnose egocentric and allocentric hemineglect. Future studies will deepen the assessment and understanding of the different forms of hemineglect by testing the motor component of the test in order to use this accurate and integrative measure in daily clinical routine

Does observation of a disabled child's action moderate action execution? Implication for the use of Action Observation Therapy for patient rehabilitation

BACKGROUND: Research investigating action observation-execution priming has mainly manipulated congruent versus incongruent action, and aspects of action expertise/capability. More specifically, the literature suggests enhanced performance priming following action observation by actors closely matched to participant expertise. The aim of the present study was to extend the understanding of action expertise effects by investigating action priming in healthy participants after observing a mild hemiparetic child actor versus a neurologically healthy child actor. METHODS: 16 healthy right-handed children, aged 6-13 years were tested. Several motor assessments were performed, including gross and fine manual motor ability, and upper limb kinematics measured using a precise robotic device. A cross-over design consisted in two experimental conditions (observing actions performed by a child with hemiparesis versus observing actions performed by a healthy child) and a pre-observation double baseline control condition, with the data analyzed using repeated measures ANOVA. RESULTS: Relative to baseline, both types of action observation conditions enhanced fine manual dexterity, but observing the hemiparetic child enhanced gross manual dexterity and upper limb velocity kinematics relative to observing actions performed by a healthy child. No effects were shown on measures of smoothness and accuracy. DISCUSSION: Contradictorily to hypotheses discussed in the literature, results here showed evidence of enhanced action execution when healthy children observed hemiparetic compared to healthy child actions. These results are discussed in terms of how patient compared to healthy actors may be useful for clinical action observation priming therapy

Mental arithmetic shifts spatial attention: Evidence from a temporal order judgement task

People often rely on a visuospatial medium to manipulate numbers. Previous studies showed that numbers are generally represented in ascending order on a left-to-right oriented continuum. Because the representation of numbers is spatially oriented, it has been assumed that solving arithmetic problems involves shifting attention toward the side of the continuum where the answer is represented. We predict that the interaction between mental arithmetic and spatial attention is determined by the relative position of the answer on the visuospatial continuum: subtraction should shift attention leftward because the answer is smaller than the first operand, whereas addition should shift attention rightward because the answer is larger than the operands. In the present study, we used a temporal order judgement task to evidence the attention biases induced by arithmetic operations. Participants had to determine which of a left or right target appeared first on the screen while solving subtraction and addition problems. The targets were flashed with different stimulus onset asynchronies to find the asynchrony at which participants gave an equal proportion of left and right responses. Results showed that this point was larger when participants were solving subtraction problems compared to addition problems, meaning that the right target should be presented several milliseconds in advance to the left target to be perceived as simultaneous during subtraction. This finding indicates that attention was biased to the left side of space during subtraction compared to addition. We conclude from these results that mental arithmetic shares common resources with spatial attention

Spatial biases in mental arithmetic are independent of reading direction habits

Studies suggest that numbers are represented in ascending order on a left-to-right oriented continuum in Western cultures. An influential framework attributes the construction of these spatial-numerical associations (SNAs) to cultural factors as, SNAs were found to be reduced or inverted in right-to-left reading cultures (e.g., Arabic). Because the representation of numbers is spatially oriented, it has been assumed that solving arithmetic problems involves shifting attention toward the side of the continuum where the answer is represented. In the present study, we used a temporal order judgement task to evidence the spatial biases induced by solving arithmetic operation problems in monolingual French and Arabic speakers. Participants had to determine which of a left or right target appeared first on the screen while solving subtraction and addition problems. We observed that the right target should be presented several milliseconds before the left target to be perceived as simultaneous during subtraction. This finding indicates that attention was biased to the left side of space during subtraction compared to addition. Importantly, this was observed for both French and Arabic participants. Our results thus indicate that the orientation of reading does not determine the direction of SNAs in mental arithmetic

Where is attention while calculating? Evidence from a temporal order judgement task

People often rely on a visuospatial medium to manipulate numbers. Previous studies showed that numbers are generally represented in ascending order on a left-to-right oriented continuum. Because the representation of numbers is spatially oriented, it has been assumed that solving arithmetic problems involves shifting attention toward the side of the continuum where the answer is represented. Based on previous work in neglect patients, we predict that the interaction between mental arithmetic and spatial attention is determined by the relative position of the answer on the visuospatial continuum: subtraction should shift attention leftward because the answer is smaller than the first operand, whereas addition should shift attention rightward because the answer is larger than the operands. In the present study, we used a temporal order judgement task to evidence the attention biases induced by arithmetic operations. Participants had to determine which of a left or right target appeared first on the screen while solving subtraction and addition problems. The left and right targets were flashed with different stimulus onset asynchronies to find the asynchrony at which participants gave an equal proportion of left and right responses. Results showed that this point of subjective simultaneity was larger when participants were solving subtraction problems compared to addition problems, meaning that the right target should be presented several milliseconds in advance to the left target to be perceived as simultaneous during subtraction. This finding indicates that attention was biased to the left side of space during subtraction compared to addition. The just noticeable difference was also larger when participants were solving subtraction problems compared to addition problems, indicating that subtraction decreased sensitivity to temporal asynchronies between the left and right targets. We conclude from these results that mental arithmetic shares common resources with spatial attention