Autism is a neurodevelopmental disorder characterized by impaired social skills, motor and percep... more Autism is a neurodevelopmental disorder characterized by impaired social skills, motor and perceptual atypicalities. These difficulties were explained within the Bayesian framework as either reflecting oversensitivity to prediction errors or – just the opposite – slow updating of such errors. To test these opposing theories, we administer paced finger-tapping, a synchronization task that requires use of recent sensory information for fast error-correction. We use computational modelling to disentangle the contributions of error-correction from that of noise in keeping temporal intervals, and in executing motor responses. To assess the specificity of tapping characteristics to autism, we compare performance to both neurotypical individuals and individuals with dyslexia. Only the autism group shows poor sensorimotor synchronization. Trial-by-trial modelling reveals typical noise levels in interval representations and motor responses. However, rate of error correction is reduced in aut...
Autism is a developmental disorder characterized by impaired social skills and accompanied by mot... more Autism is a developmental disorder characterized by impaired social skills and accompanied by motor and perceptual atypicalities. Its etiology is an open question, partly due to the diverse range of associated difficulties. Based on recent observations that individuals with autism are slow in updating perceptual priors, we now hypothesized that motor updating is also slow. Slow motor updating is expected to hamper the ability to synchronize to external events, since asynchronies are corrected sluggishly. Since sensorimotor synchronization is important for social bonding and cooperation, its impairment is expected to impair social skills. To test this hypothesis, we measured paced finger tapping to a metronome in neurotypical, ASD, and dyslexia groups. Dyslexia was assessed as a control group with a non-social neurodevelopmental atypicality. Only the ASD group showed reduced sensorimotor synchronization. Trial-by-trial computational modelling revealed that their ability to form contr...
Reduced short-term memory (STM) of individuals with dyslexia (IDDs) and enhanced STM of musicians... more Reduced short-term memory (STM) of individuals with dyslexia (IDDs) and enhanced STM of musicians are well documented, yet their causes are disputed. We hypothesized that their STMs reflect their sensitivities to accumulative long-term stimuli statistics. Indeed, when performing an STM task, IDDs had reduced benefit from syllable frequency, whereas musicians manifested an opposite effect, compared to controls. Interestingly, benefit from sequence-repetition did not significantly differ between groups, suggesting that it relies on different mechanisms. To test the generality of this separation across populations, we recruited a group of good-readers, whose native language contains a smaller fraction of the high-frequency syllables. Their span for these "high-frequency" syllables was small, yet their benefit from sequence-repetition was adequate. These experiments indicate that sensitivity to long-term stimuli distribution, and not to sequential repetition, is reduced in IDD...
Journal of Experimental Psychology: Learning, Memory, and Cognition, 2019
Are difficulties of individuals with dyslexia (IDDs) reduced or enhanced in tasks where linguisti... more Are difficulties of individuals with dyslexia (IDDs) reduced or enhanced in tasks where linguistic regularities typically facilitate performance, such as vocabulary acquisition and reading? If impaired short-term memory and poor phonological decoding pose the main impediments to IDDs, then they are expected to compensate for these difficulties with a greater reliance on linguistic regularities, to reduce online load. However, if reduced benefits from regularities pose the main bottleneck, IDDs might benefit less than good readers from regularities in spite of their online difficulties. To test that, we administered two experiments. In a novel paradigm of auditory vocabulary acquisition in Hebrew, novel words were presented either with or without familiar morphological structure. Participants with dyslexia showed a reduced recall benefit from familiar structure as compared with controls. However, their recognition was facilitated by morphological structure and did not significantly differ from controls'. In the second experiment, participants read novel words with and without familiar structure. Benefit from structure familiarity for IDDs was significantly smaller than for controls, in spite of IDDs' greater potential benefit from familiar structure due to their reduced overall accuracy. However, when asked to emphasize speed in reading, structure familiarity was found to be beneficial for IDDs, without compromising accuracy. These results imply that accumulative acquisition of sublexical regularities is less efficient in dyslexia, though in some tasks this knowledge is accessible and beneficial. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
Dyslexia is a prevalent reading disability whose underlying mechanisms are still disputed. We stu... more Dyslexia is a prevalent reading disability whose underlying mechanisms are still disputed. We studied the neural mechanisms underlying dyslexia using a simple frequency-discrimination task. Though participants were asked to compare the two tones in each trial, implicit memory of previous trials affected their responses. We hypothesized that implicit memory decays faster among dyslexics. We tested this by increasing the temporal intervals between consecutive trials, and by measuring the behavioral impact and ERP responses from the auditory cortex. Dyslexics showed a faster decay of implicit memory effects on both measures, with similar time constants. Finally, faster decay of implicit memory also characterized the impact of sound regularities in benefitting dyslexics' oral reading rate. Their benefit decreased faster as a function of the time interval from the previous reading of the same non-word. We propose that dyslexics' shorter neural adaptation paradoxically accounts fo...
Dyslexics are diagnosed for their poor reading skills, yet they characteristically also suffer fr... more Dyslexics are diagnosed for their poor reading skills, yet they characteristically also suffer from poor verbal memory and often from poor auditory skills. To date, this combined profile has been accounted for in broad cognitive terms. Here we hypothesize that the perceptual deficits associated with dyslexia can be understood computationally as a deficit in integrating prior information with noisy observations. To test this hypothesis we analyzed the performance of human participants in an auditory discrimination task using a two-parameter computational model. One parameter captures the internal noise in representing the current event, and the other captures the impact of recently acquired prior information. Our findings show that dyslexics' perceptual deficit can be accounted for by inadequate adjustment of these components; namely, low weighting of their implicit memory of past trials relative to their internal noise. Underweighting the stimulus statistics decreased dyslexics&...
Autism is a neurodevelopmental disorder characterized by impaired social skills, motor and percep... more Autism is a neurodevelopmental disorder characterized by impaired social skills, motor and perceptual atypicalities. These difficulties were explained within the Bayesian framework as either reflecting oversensitivity to prediction errors or – just the opposite – slow updating of such errors. To test these opposing theories, we administer paced finger-tapping, a synchronization task that requires use of recent sensory information for fast error-correction. We use computational modelling to disentangle the contributions of error-correction from that of noise in keeping temporal intervals, and in executing motor responses. To assess the specificity of tapping characteristics to autism, we compare performance to both neurotypical individuals and individuals with dyslexia. Only the autism group shows poor sensorimotor synchronization. Trial-by-trial modelling reveals typical noise levels in interval representations and motor responses. However, rate of error correction is reduced in aut...
Autism is a developmental disorder characterized by impaired social skills and accompanied by mot... more Autism is a developmental disorder characterized by impaired social skills and accompanied by motor and perceptual atypicalities. Its etiology is an open question, partly due to the diverse range of associated difficulties. Based on recent observations that individuals with autism are slow in updating perceptual priors, we now hypothesized that motor updating is also slow. Slow motor updating is expected to hamper the ability to synchronize to external events, since asynchronies are corrected sluggishly. Since sensorimotor synchronization is important for social bonding and cooperation, its impairment is expected to impair social skills. To test this hypothesis, we measured paced finger tapping to a metronome in neurotypical, ASD, and dyslexia groups. Dyslexia was assessed as a control group with a non-social neurodevelopmental atypicality. Only the ASD group showed reduced sensorimotor synchronization. Trial-by-trial computational modelling revealed that their ability to form contr...
Reduced short-term memory (STM) of individuals with dyslexia (IDDs) and enhanced STM of musicians... more Reduced short-term memory (STM) of individuals with dyslexia (IDDs) and enhanced STM of musicians are well documented, yet their causes are disputed. We hypothesized that their STMs reflect their sensitivities to accumulative long-term stimuli statistics. Indeed, when performing an STM task, IDDs had reduced benefit from syllable frequency, whereas musicians manifested an opposite effect, compared to controls. Interestingly, benefit from sequence-repetition did not significantly differ between groups, suggesting that it relies on different mechanisms. To test the generality of this separation across populations, we recruited a group of good-readers, whose native language contains a smaller fraction of the high-frequency syllables. Their span for these "high-frequency" syllables was small, yet their benefit from sequence-repetition was adequate. These experiments indicate that sensitivity to long-term stimuli distribution, and not to sequential repetition, is reduced in IDD...
Journal of Experimental Psychology: Learning, Memory, and Cognition, 2019
Are difficulties of individuals with dyslexia (IDDs) reduced or enhanced in tasks where linguisti... more Are difficulties of individuals with dyslexia (IDDs) reduced or enhanced in tasks where linguistic regularities typically facilitate performance, such as vocabulary acquisition and reading? If impaired short-term memory and poor phonological decoding pose the main impediments to IDDs, then they are expected to compensate for these difficulties with a greater reliance on linguistic regularities, to reduce online load. However, if reduced benefits from regularities pose the main bottleneck, IDDs might benefit less than good readers from regularities in spite of their online difficulties. To test that, we administered two experiments. In a novel paradigm of auditory vocabulary acquisition in Hebrew, novel words were presented either with or without familiar morphological structure. Participants with dyslexia showed a reduced recall benefit from familiar structure as compared with controls. However, their recognition was facilitated by morphological structure and did not significantly differ from controls'. In the second experiment, participants read novel words with and without familiar structure. Benefit from structure familiarity for IDDs was significantly smaller than for controls, in spite of IDDs' greater potential benefit from familiar structure due to their reduced overall accuracy. However, when asked to emphasize speed in reading, structure familiarity was found to be beneficial for IDDs, without compromising accuracy. These results imply that accumulative acquisition of sublexical regularities is less efficient in dyslexia, though in some tasks this knowledge is accessible and beneficial. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
Dyslexia is a prevalent reading disability whose underlying mechanisms are still disputed. We stu... more Dyslexia is a prevalent reading disability whose underlying mechanisms are still disputed. We studied the neural mechanisms underlying dyslexia using a simple frequency-discrimination task. Though participants were asked to compare the two tones in each trial, implicit memory of previous trials affected their responses. We hypothesized that implicit memory decays faster among dyslexics. We tested this by increasing the temporal intervals between consecutive trials, and by measuring the behavioral impact and ERP responses from the auditory cortex. Dyslexics showed a faster decay of implicit memory effects on both measures, with similar time constants. Finally, faster decay of implicit memory also characterized the impact of sound regularities in benefitting dyslexics' oral reading rate. Their benefit decreased faster as a function of the time interval from the previous reading of the same non-word. We propose that dyslexics' shorter neural adaptation paradoxically accounts fo...
Dyslexics are diagnosed for their poor reading skills, yet they characteristically also suffer fr... more Dyslexics are diagnosed for their poor reading skills, yet they characteristically also suffer from poor verbal memory and often from poor auditory skills. To date, this combined profile has been accounted for in broad cognitive terms. Here we hypothesize that the perceptual deficits associated with dyslexia can be understood computationally as a deficit in integrating prior information with noisy observations. To test this hypothesis we analyzed the performance of human participants in an auditory discrimination task using a two-parameter computational model. One parameter captures the internal noise in representing the current event, and the other captures the impact of recently acquired prior information. Our findings show that dyslexics' perceptual deficit can be accounted for by inadequate adjustment of these components; namely, low weighting of their implicit memory of past trials relative to their internal noise. Underweighting the stimulus statistics decreased dyslexics&...
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