Marie-chantal Wanet-defalque | Université de Montréal (original) (raw)
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Papers by Marie-chantal Wanet-defalque
Site design criteria for wide open spaces are often based on aesthetic concerns and safe crowd mo... more Site design criteria for wide open spaces are often based on aesthetic concerns and safe crowd movements. These criteria consequently led the designers of the Montreal Place of Festivals to suggest levelling sidewalks and streets and prohibition of vehicle traffic during the warm season (six months). Use of guidance tiles has been proposed and its relevance examined by the Accessibility Committee since blind people were losing cues normally used for traveling in a straight line and for localizing street corners. Though many countries install tactile surfaces in such areas in order to facilitate travel by the blind or visually impaired persons, the effectiveness of these surfaces in cities with long winter periods has not been demonstrated. Also, guidance lines have not yet been applied in North America. This pilot project intended to test the effectiveness of this type of application in winter conditions. The objectives of the project were (1) to assess the capability of a blind per...
Investigative ophthalmology & visual science, 2001
To explore electrically induced phosphenes in blind patients with retinitis pigmentosa (RP) in co... more To explore electrically induced phosphenes in blind patients with retinitis pigmentosa (RP) in comparison with healthy subjects and to develop a screening test for candidates for an optic nerve visual prosthesis implantation. Phosphenes are obtained by charge balanced biphasic pulse stimulations through a surface cathode over the closed eyelids and an anode near the opposite ear. The resulting strength-duration relationship for somatosensory, phosphene, and pain threshold has been recorded in five RP patients as well as in 10 healthy volunteers. In sighted subjects, the average rheobase and chronaxy for phosphene perception are 0.28 mA and 3.07 msec, respectively. For pulse durations longer than 2 msec, phosphenes are usually obtained at current strengths below the level giving rise to any other electrically generated sensation. In RP patients, however, phosphenes are not so easily obtained. One in five had no visual response at all. Another patient reported a flash perception for t...
Perception, 1999
Recognition tasks of simple visual patterns have been used to assess an early visual--auditory se... more Recognition tasks of simple visual patterns have been used to assess an early visual--auditory sensory-substitution system, consisting of the coupling of a rough model of the human retina with an inverse model of the cochlea, by means of a pixel-frequency relationship. The potential advantage of the device, compared with previous ones, is to give the blind the ability to both localise and recognise visual patterns. Four evaluation sessions assessed the performance of twenty-four blindfolded sighted subjects using the device. Subjects had to recognise twenty-five visual patterns, one at a time, using a head-mounted small camera and interpreting the corresponding sounds given by the device. Half the subjects were trained by means of a correction feedback procedure during ten one-hour training sessions embedded in between the evaluation sessions. Results revealed extremely successful training effects. Performance of trained subjects significantly increased with practice compared with the untrained control group. The improvement was also observed for new patterns, demonstrating a learning-process generalisation. The negative correlation observed between scores and processing time showed that the subjects' response accuracy was related to their speed. In conclusion, simple pattern recognition is possible with a fairly natural vision-to-audition coding scheme, given the possibility for the subjects to have sensory--motor interactions while using the device.
NeuroImage, 2001
This PET study aimed at investigating the neural structures involved in pattern recognition in ea... more This PET study aimed at investigating the neural structures involved in pattern recognition in early blind subjects using sensory substitution equipment (SSE). Six early blind and six blindfolded sighted subjects were studied during three auditory processing tasks: a detection task with noise stimuli, a detection task with familiar sounds, and a pattern recognition task using the SSE. The results showed a differential activation pattern with the SSE as a function of the visual experience: in addition to the regions involved in the recognition process in sighted control subjects, occipital areas of early blind subjects were also activated. The occipital activation was more important when the early blind subjects used SSE than during the other auditory tasks. These results suggest that activity of the extrastriate visual cortex of early blind subjects can be modulated and bring additional evidence that early visual deprivation leads to cross-modal cerebral reorganization.
Experimental Brain Research, 1986
The locomotor behaviour of adult cats blinded soon after birth was compared to that of control ca... more The locomotor behaviour of adult cats blinded soon after birth was compared to that of control cats by measuring running time in a maze. The effects of vibrissae deprivation in trained blind and control cats and of visual deprivation in control cats was studied. The performance of the control cats decreased in darkness to the level reached by the blind cats. Deprivation of vibrissae affected the performance of the control cats only in darkness and had no effect on the blind cats. The role played by various sensory systems in locomotion during development and in adulthood is discussed.
Disability & Rehabilitation, 2010
Disability & Rehabilitation, 2009
(1) to document participation in daily activities and social roles of older adults seeking servic... more (1) to document participation in daily activities and social roles of older adults seeking services for visual impairment (VI) and compare it with that of the older population without VI or other disabilities, and (2) to explore correlates of their participation. The 64 participants (46 women) had an average age of 79.3 years (SD = 5.9 years) and presented various types of VI. Participants were interviewed at home to collect information regarding their visual function (National Eye Institute Visual Function Questionnaire-25), sociodemographic and clinical characteristics, including depressive symptoms (Geriatric Depression Scale), and participation (Assessment of Life Habits/LIFE-H). Each participant was matched with another person without disabilities randomly recruited from the community. Results for the two populations on the Life-H participation domains were compared using t-tests. In the group with VI, general information (independent variables) was examined in relation to participation main scores (dependent variables), followed by multiple linear regression analyses. Participation in daily activities and social roles of participants with VI (mean +/- SD (/9) = 6.8 +/- 1.0 and 5.6 +/- 1.6, respectively) was significantly lower than that of participants without VI (8.1 +/- 0.4 and 8.3 +/- 0.4) (p < 0.0001). Depressive symptoms and perceived quality of distance vision were the strongest correlates and together explained more than 65% of the variance in the participation scores of the subjects with VI. This study demonstrates the participation restrictions associated with VI and underlines the importance of psychological aspects in participation.
British Journal of Visual Impairment, 2013
ABSTRACT The objective of this study was to explore the pattern of adaptation in patients who hav... more ABSTRACT The objective of this study was to explore the pattern of adaptation in patients who have been diagnosed with visual impairment. Participants (N = 700), recruited in the Montreal area (Canada), underwent a structured interview in order to collect information on the duration of the acquired visual impairment and answered the ‘Brief Cope’, ‘Satisfaction with Life Scale’ and ‘Center for Epidemiologic Studies–Depression Scale’ (CES-D). Multivariate analysis of covariance (MANCOVA) revealed that patients who have lived with vision impairment for over 2 years reach significantly higher acceptance and lower denial levels compared to those of patients who had recent vision loss (≤2 years). We also found that acceptance was positively correlated with well-being and denial with depression, while acceptance was negatively correlated with depression and, likewise, denial with well-being. Our study results suggest that patients who have been diagnosed with visual impairment engage in an adaptative coping style early in the grief process.
Behavioral Neuroscience, 1992
The aim of this study was to design an animal model of sensory substitution in the case of blindn... more The aim of this study was to design an animal model of sensory substitution in the case of blindness. Six kittens were binocularly enucleated; as adults, they were fitted with an ultrasonic echolocation prosthesis. This device provided the animals with auditory signals that coded distance and direction of obstacles. Animals were trained by operant conditioning to use the prosthesis in various behavioral situation. The results showed that visually deprived animals tried to solve the task using natural information and that they only used artificial information provided by the prosthesis when they were unable to succeed with natural cues. Under these conditions, it was asserted that in a jumping test these animals evaluated depth by means of the prosthesis; in a locomotion task in a maze, it was also demonstrated that they could use the prosthesis for avoiding obstacles.
Acta Psychologica, 2004
An active visuo-spatial memory task was used in order to determine the characteristics of mental ... more An active visuo-spatial memory task was used in order to determine the characteristics of mental imagery in subjects with and without visual experience. Subjects were instructed to generate a mental representation of verbally presented 2D patterns that were placed in a grid and to indicate how many pattern elements were in corresponding positions in the two halves of the grid according to a specific grid axis (vertical or horizontal). Unexpectedly, results showed a similar performance in early blind, late blind and sighted subjects. However, subjects' debriefing showed that the three groups used different strategies. The sighted and the late blind subjects took advantage of a visuo-spatial strategy. They generated a mental image of the matrix and they simplified this image to maintain only the relevant information in memory. In contrast, the early blind subjects encoded each pattern element by its location in a (X,Y) coordinate system without visual representation. This indicates that both early and late blind subjects are able to perform an active visuo-spatial imagery task as well as sighted subjects although they use different strategies.
Site design criteria for wide open spaces are often based on aesthetic concerns and safe crowd mo... more Site design criteria for wide open spaces are often based on aesthetic concerns and safe crowd movements. These criteria consequently led the designers of the Montreal Place of Festivals to suggest levelling sidewalks and streets and prohibition of vehicle traffic during the warm season (six months). Use of guidance tiles has been proposed and its relevance examined by the Accessibility Committee since blind people were losing cues normally used for traveling in a straight line and for localizing street corners. Though many countries install tactile surfaces in such areas in order to facilitate travel by the blind or visually impaired persons, the effectiveness of these surfaces in cities with long winter periods has not been demonstrated. Also, guidance lines have not yet been applied in North America. This pilot project intended to test the effectiveness of this type of application in winter conditions. The objectives of the project were (1) to assess the capability of a blind per...
Investigative ophthalmology & visual science, 2001
To explore electrically induced phosphenes in blind patients with retinitis pigmentosa (RP) in co... more To explore electrically induced phosphenes in blind patients with retinitis pigmentosa (RP) in comparison with healthy subjects and to develop a screening test for candidates for an optic nerve visual prosthesis implantation. Phosphenes are obtained by charge balanced biphasic pulse stimulations through a surface cathode over the closed eyelids and an anode near the opposite ear. The resulting strength-duration relationship for somatosensory, phosphene, and pain threshold has been recorded in five RP patients as well as in 10 healthy volunteers. In sighted subjects, the average rheobase and chronaxy for phosphene perception are 0.28 mA and 3.07 msec, respectively. For pulse durations longer than 2 msec, phosphenes are usually obtained at current strengths below the level giving rise to any other electrically generated sensation. In RP patients, however, phosphenes are not so easily obtained. One in five had no visual response at all. Another patient reported a flash perception for t...
Perception, 1999
Recognition tasks of simple visual patterns have been used to assess an early visual--auditory se... more Recognition tasks of simple visual patterns have been used to assess an early visual--auditory sensory-substitution system, consisting of the coupling of a rough model of the human retina with an inverse model of the cochlea, by means of a pixel-frequency relationship. The potential advantage of the device, compared with previous ones, is to give the blind the ability to both localise and recognise visual patterns. Four evaluation sessions assessed the performance of twenty-four blindfolded sighted subjects using the device. Subjects had to recognise twenty-five visual patterns, one at a time, using a head-mounted small camera and interpreting the corresponding sounds given by the device. Half the subjects were trained by means of a correction feedback procedure during ten one-hour training sessions embedded in between the evaluation sessions. Results revealed extremely successful training effects. Performance of trained subjects significantly increased with practice compared with the untrained control group. The improvement was also observed for new patterns, demonstrating a learning-process generalisation. The negative correlation observed between scores and processing time showed that the subjects' response accuracy was related to their speed. In conclusion, simple pattern recognition is possible with a fairly natural vision-to-audition coding scheme, given the possibility for the subjects to have sensory--motor interactions while using the device.
NeuroImage, 2001
This PET study aimed at investigating the neural structures involved in pattern recognition in ea... more This PET study aimed at investigating the neural structures involved in pattern recognition in early blind subjects using sensory substitution equipment (SSE). Six early blind and six blindfolded sighted subjects were studied during three auditory processing tasks: a detection task with noise stimuli, a detection task with familiar sounds, and a pattern recognition task using the SSE. The results showed a differential activation pattern with the SSE as a function of the visual experience: in addition to the regions involved in the recognition process in sighted control subjects, occipital areas of early blind subjects were also activated. The occipital activation was more important when the early blind subjects used SSE than during the other auditory tasks. These results suggest that activity of the extrastriate visual cortex of early blind subjects can be modulated and bring additional evidence that early visual deprivation leads to cross-modal cerebral reorganization.
Experimental Brain Research, 1986
The locomotor behaviour of adult cats blinded soon after birth was compared to that of control ca... more The locomotor behaviour of adult cats blinded soon after birth was compared to that of control cats by measuring running time in a maze. The effects of vibrissae deprivation in trained blind and control cats and of visual deprivation in control cats was studied. The performance of the control cats decreased in darkness to the level reached by the blind cats. Deprivation of vibrissae affected the performance of the control cats only in darkness and had no effect on the blind cats. The role played by various sensory systems in locomotion during development and in adulthood is discussed.
Disability & Rehabilitation, 2010
Disability & Rehabilitation, 2009
(1) to document participation in daily activities and social roles of older adults seeking servic... more (1) to document participation in daily activities and social roles of older adults seeking services for visual impairment (VI) and compare it with that of the older population without VI or other disabilities, and (2) to explore correlates of their participation. The 64 participants (46 women) had an average age of 79.3 years (SD = 5.9 years) and presented various types of VI. Participants were interviewed at home to collect information regarding their visual function (National Eye Institute Visual Function Questionnaire-25), sociodemographic and clinical characteristics, including depressive symptoms (Geriatric Depression Scale), and participation (Assessment of Life Habits/LIFE-H). Each participant was matched with another person without disabilities randomly recruited from the community. Results for the two populations on the Life-H participation domains were compared using t-tests. In the group with VI, general information (independent variables) was examined in relation to participation main scores (dependent variables), followed by multiple linear regression analyses. Participation in daily activities and social roles of participants with VI (mean +/- SD (/9) = 6.8 +/- 1.0 and 5.6 +/- 1.6, respectively) was significantly lower than that of participants without VI (8.1 +/- 0.4 and 8.3 +/- 0.4) (p < 0.0001). Depressive symptoms and perceived quality of distance vision were the strongest correlates and together explained more than 65% of the variance in the participation scores of the subjects with VI. This study demonstrates the participation restrictions associated with VI and underlines the importance of psychological aspects in participation.
British Journal of Visual Impairment, 2013
ABSTRACT The objective of this study was to explore the pattern of adaptation in patients who hav... more ABSTRACT The objective of this study was to explore the pattern of adaptation in patients who have been diagnosed with visual impairment. Participants (N = 700), recruited in the Montreal area (Canada), underwent a structured interview in order to collect information on the duration of the acquired visual impairment and answered the ‘Brief Cope’, ‘Satisfaction with Life Scale’ and ‘Center for Epidemiologic Studies–Depression Scale’ (CES-D). Multivariate analysis of covariance (MANCOVA) revealed that patients who have lived with vision impairment for over 2 years reach significantly higher acceptance and lower denial levels compared to those of patients who had recent vision loss (≤2 years). We also found that acceptance was positively correlated with well-being and denial with depression, while acceptance was negatively correlated with depression and, likewise, denial with well-being. Our study results suggest that patients who have been diagnosed with visual impairment engage in an adaptative coping style early in the grief process.
Behavioral Neuroscience, 1992
The aim of this study was to design an animal model of sensory substitution in the case of blindn... more The aim of this study was to design an animal model of sensory substitution in the case of blindness. Six kittens were binocularly enucleated; as adults, they were fitted with an ultrasonic echolocation prosthesis. This device provided the animals with auditory signals that coded distance and direction of obstacles. Animals were trained by operant conditioning to use the prosthesis in various behavioral situation. The results showed that visually deprived animals tried to solve the task using natural information and that they only used artificial information provided by the prosthesis when they were unable to succeed with natural cues. Under these conditions, it was asserted that in a jumping test these animals evaluated depth by means of the prosthesis; in a locomotion task in a maze, it was also demonstrated that they could use the prosthesis for avoiding obstacles.
Acta Psychologica, 2004
An active visuo-spatial memory task was used in order to determine the characteristics of mental ... more An active visuo-spatial memory task was used in order to determine the characteristics of mental imagery in subjects with and without visual experience. Subjects were instructed to generate a mental representation of verbally presented 2D patterns that were placed in a grid and to indicate how many pattern elements were in corresponding positions in the two halves of the grid according to a specific grid axis (vertical or horizontal). Unexpectedly, results showed a similar performance in early blind, late blind and sighted subjects. However, subjects' debriefing showed that the three groups used different strategies. The sighted and the late blind subjects took advantage of a visuo-spatial strategy. They generated a mental image of the matrix and they simplified this image to maintain only the relevant information in memory. In contrast, the early blind subjects encoded each pattern element by its location in a (X,Y) coordinate system without visual representation. This indicates that both early and late blind subjects are able to perform an active visuo-spatial imagery task as well as sighted subjects although they use different strategies.