Showing papers on "Perceptual learning published in 2006"

Enhanced Perceptual Functioning in Autism: An Update, and Eight Principles of Autistic Perception

Abstract: We propose an “Enhanced Perceptual Functioning” model encompassing the main differences between autistic and non-autistic social and non-social perceptual processing: locally oriented visual and auditory perception, enhanced low-level discrimination, use of a more posterior network in “complex” visual tasks, enhanced perception of first order static stimuli, diminished perception of complex movement, autonomy of low-level information processing toward higher-order operations, and differential relation between perception and general intelligence. Increased perceptual expertise may be implicated in the choice of special ability in savant autistics, and in the variability of apparent presentations within PDD (autism with and without typical speech, Asperger syndrome) in non-savant autistics. The overfunctioning of brain regions typically involved in primary perceptual functions may explain the autistic perceptual endophenotype.

Perceptual Learning Directs Auditory Cortical Map Reorganization through Top-Down Influences

Abstract: The primary sensory cortex is positioned at a confluence of bottom-up dedicated sensory inputs and top-down inputs related to higher-order sensory features, attentional state, and behavioral reinforcement We tested whether topographic map plasticity in the adult primary auditory cortex and a secondary auditory area, the suprarhinal auditory field, was controlled by the statistics of bottom-up sensory inputs or by top-down task-dependent influences Rats were trained to attend to independent parameters, either frequency or intensity, within an identical set of auditory stimuli, allowing us to vary task demands while holding the bottom-up sensory inputs constant We observed a clear double-dissociation in map plasticity in both cortical fields Rats trained to attend to frequency cues exhibited an expanded representation of the target frequency range within the tonotopic map but no change in sound intensity encoding compared with controls Rats trained to attend to intensity cues expressed an increased proportion of nonmonotonic intensity response profiles preferentially tuned to the target intensity range but no change in tonotopic map organization relative to controls The degree of topographic map plasticity within the task-relevant stimulus dimension was correlated with the degree of perceptual learning for rats in both tasks These data suggest that enduring receptive field plasticity in the adult auditory cortex may be shaped by task-specific top-down inputs that interact with bottom-up sensory inputs and reinforcement-based neuromodulator release Top-down inputs might confer the selectivity necessary to modify a single feature representation without affecting other spatially organized feature representations embedded within the same neural circuitry

Selective Attention and Transfer Phenomena in L2 Acquisition: Contingency, Cue Competition, Salience, Interference, Overshadowing, Blocking, and Perceptual Learning

Abstract: If first language is rational in the sense that acquisition produces an end-state model of language that is a proper reflection of input and that optimally prepares speakers for comprehension and production, second language is usually not. This paper considers the apparent irrationalities of L2 acquisition, that is the shortcomings where input fails to become intake. It describes how ‘learned attention’, a key concept in contemporary associative and connectionist theories of animal and human learning, explains these effects. The fragile features of L2 acquisition are those which, however available as a result of frequency, recency, or context, fall short of intake because of one of the factors of contingency, cue competition, salience, interference, overshadowing, blocking, or perceptual learning, which are all shaped by the L1. Each phenomenon is explained within associative learning theory and exemplified in language learning. Paradoxically, the successes of L1 acquisition and the limitations of L2 acquisition both derive from the same basic learning principles.

Generalization in perceptual learning for speech

Abstract: Lexical context strongly influences listeners' identification of ambiguous sounds. For example, a sound midway between /f/ and /s/ is reported as /f/ in "sheri_," but as /s/ in "Pari_." Norris, McQueen, and Cutler (2003) have demonstrated that after hearing such lexically determined phonemes, listeners expand their phonemic categories to include more ambiguous tokens than before. We tested whether listeners adjust their phonemic categories for a specific speaker. Do listeners learn a particular speaker's "accent"? Similarly, we examined whether perceptual learning is specific to the particular ambiguous phonemes that listeners hear, or whether the adjustments generalize to related sounds. Participants heard ambiguous /d/ or /t/ phonemes during a lexical decision task. They then categorized sounds on /d/-/t/ and /b/-/p/ continua, either in the same voice that they had heard for lexical decision, or in a different voice. Perceptual learning generalized across both speaker and test continua: Changes in perceptual representations are robust and broadly tuned.

Statistical Learning Within and Between Modalities Pitting Abstract Against Stimulus-Specific Representations

Abstract: When learners encode sequential patterns and generalize their knowledge to novel instances, are they relying on abstract or stimulus-specific representations? Research on artificial grammar learning (AGL) has shown transfer of learning from one stimulus set to another, and such findings have encouraged the view that statistical learning is mediated by abstract representations that are independent of the sense modality or perceptual features of the stimuli. Using a novel modification of the standard AGL paradigm, we obtained data to the contrary. These experiments pitted abstract processing against stimulus-specific learning. The findings show that statistical learning results in knowledge that is stimulus-specific rather than abstract. They show furthermore that learning can proceed in parallel for multiple input streams along separate perceptual dimensions or sense modalities. We conclude that learning sequential structure and generalizing to novel stimuli inherently involve learning mechanisms that are ...

Visual complexity: a review.

Abstract: The idea of visual complexity, the history of its measurement, and its implications for behavior are reviewed, starting with structuralism and Gestalt psychology at the beginning of the 20th century and ending with visual complexity theory, perceptual learning theory, and neural circuit theory at the beginning of the 21st. Evidence is drawn from research on single forms, form and texture arrays and visual displays. Form complexity and form probability are shown to be linked through their reciprocal relationship in complexity theory, which is in turn shown to be consistent with recent developments in perceptual learning and neural circuit theory. Directions for further research are suggested.

Learning to See the Difference Specifically Alters the Most Informative V4 Neurons

Abstract: Perceptual learning is an instance of adult plasticity whereby training in a sensory (e.g., a visual task) results in neuronal changes leading to an improved ability to perform the task. Yet studies in primary visual cortex have found that changes in neuronal response properties were relatively modest. The present study examines the effects of training in an orientation discrimination task on the response properties of V4 neurons in awake rhesus monkeys. Results indicate that the changes induced in V4 are indeed larger than those in V1. Nonspecific effects of training included a decrease in response variance, and an increase in overall orientation selectivity in V4. The orientation-specific changes involved a local steepening in the orientation tuning curve around the trained orientation that selectively improved orientation discriminability at the trained orientation. Moreover, these changes were largely confined to the population of neurons whose orientation tuning was optimal for signaling small differences in orientation at the trained orientation. Finally, the modifications were restricted to the part of the tuning curve close to the trained orientation. Thus, we conclude that it is the most informative V4 neurons, those most directly involved in the discrimination, that are specifically modified by perceptual learning.

Performance Feedback Drives Caudate Activation in a Phonological Learning Task

Abstract: Adults have difficulty discriminating nonnative phonetic contrasts, but under certain circumstances training can lead to improvement in this ability. Despite the ubiquitous use of performance feedback in training paradigms in this and many other domains, the mechanisms by which feedback affects learning are not well understood. In this event-related functional magnetic resonance imaging study, we examined how performance feedback is processed during perceptual learning. Thirteen Japanese speakers for whom the English phonemes [r] and [l] were nondistinct performed an identification task of the words “road” and “load” that has been shown to be effective in inducing learning only when performance feedback is present. Each subject performed alternating runs of training with and without feedback, followed by performance of a card-guessing task with monetary reward and punishment outcomes. We found that the caudate nucleus was more robustly activated bilaterally when performing the perceptual identification task with feedback than without feedback, and the right caudate nucleus also showed a differential response to positive and negative feedback. Moreover, using a within-subjects design, we found that the caudate nucleus also showed a similar activation pattern to monetary reward and punishment outcomes in the card-guessing task. These results demonstrate that the caudate responds to positive and negative feedback during learning in a manner analogous to its processing of extrinsic affective reinforcers and indicate that this region may be a critical moderator of the influence of feedback on learning. These findings impact our broader understanding of the mechanisms underlying nondeclarative learning and language acquisition.

Perceptual learning style and learning proficiency: A test of the hypothesis.

Abstract: Given the potential importance of using modality preference with instruction, the authors tested whether learning style preference correlated with memory performance in each of 3 sensory modalities: visual, auditory, and kinesthetic. In Study 1, participants completed objective measures of pictorial, auditory, and tactile learning and learning style self-assessments. The results indicate that objective test performance did not correlate with learning style preference. In Study 2, the authors examined in more detail the information participants used to answer the learning style self-assessment. The findings indicate that participants answered the inventory using general memories and beliefs rather than specific examples of learning in different modalities. These results challenge the hypothesis that individuals learn best with material presented in a particular sensory modality.

Discrimination learning induced by training with identical stimuli

Abstract: Sensory stimuli become easier to detect or distinguish with practice. It is generally assumed that the task-relevant stimulus dimension becomes increasingly more salient as a result of attentively performing the task at a level that is neither too easy nor too difficult. However, here we show improved auditory frequency discrimination following training with physically identical tones that were impossible to discriminate. We also show that learning transfers across tone frequencies and across modalities: training on a silent visuospatial computer game improved thresholds on the auditory discrimination task. We suggest that three processes are necessary for optimal perceptual learning: sensitization through exposure to the stimulus, modality- and dimension-specific attention, and general arousal.

Training-induced plasticity of auditory localization in adult mammals

Abstract: Accurate auditory localization relies on neural computations based on spatial cues present in the sound waves at each ear. The values of these cues depend on the size, shape, and separation of the two ears and can therefore vary from one individual to another. As with other perceptual skills, the neural circuits involved in spatial hearing are shaped by experience during development and retain some capacity for plasticity in later life. However, the factors that enable and promote plasticity of auditory localization in the adult brain are unknown. Here we show that mature ferrets can rapidly relearn to localize sounds after having their spatial cues altered by reversibly occluding one ear, but only if they are trained to use these cues in a behaviorally relevant task, with greater and more rapid improvement occurring with more frequent training. We also found that auditory adaptation is possible in the absence of vision or error feedback. Finally, we show that this process involves a shift in sensitivity away from the abnormal auditory spatial cues to other cues that are less affected by the earplug. The mature auditory system is therefore capable of adapting to abnormal spatial information by reweighting different localization cues. These results suggest that training should facilitate acclimatization to hearing aids in the hearing impaired.

Perceptual learning in speech: Stability over time (L)

Abstract: Perceptual representations of phonemes are flexible and adapt rapidly to accommodate idiosyncratic articulation in the speech of a particular talker. This letter addresses whether such adjustments remain stable over time and under exposure to other talkers. During exposure to a story, listeners learned to interpret an ambiguous sound as [f] or [s]. Perceptual adjustments measured after 12 h were as robust as those measured immediately after learning. Equivalent effects were found when listeners heard speech from other talkers in the 12 h interval, and when they had the opportunity to consolidate learning during sleep.

Changes in Auditory Cortex Parallel Rapid Perceptual Learning

Abstract: Learning perceptual skills is characterized by rapid improvements in performance within the first hour of training (fast perceptual learning) followed by more gradual improvements that take place over several daily practice sessions (slow perceptual learning). Although it is widely accepted that slow perceptual learning is accompanied by enhanced stimulus representation in sensory cortices, there is considerable controversy about the neural substrates underlying early and rapid improvements in learning perceptual skills. Here we measured event-related brain potentials while listeners were presented with 2 phonetically different vowels. Listeners' ability to identify both vowels improved gradually during the first hour of testing and was paralleled by enhancements in an early evoked response ( approximately 130 ms) localized in the right auditory cortex and a late evoked response ( approximately 340 ms) localized in the right anterior superior temporal gyrus and/or inferior prefrontal cortex. These neuroplastic changes depended on listeners' attention and were preserved only if practice was continued; familiarity with the task structure (procedural learning) was not sufficient. We propose that the early increases in cortical responsiveness reflect goal-directed changes in the tuning properties of auditory neurons involved in parsing concurrent speech signals. Importantly, the neuroplastic changes occurred rapidly, demonstrating the flexibility of human speech segregation mechanisms.

Tactile coactivation resets age‐related decline of human tactile discrimination

Abstract: Objective: For young subjects, it is well-documented that training and practice improve sensorimotor performance. However, little is known about how the typically observed age-related decline of sensorimotor abilities can be ameliorated by sensory stimulation. Methods: As an alternative approach to training, we have introduced a tactile coactivation protocol involving Hebbian synaptic plasticity to improve tactile performance on a short timescale of a few hours. Results: By applying coactivation on the index finger to drive perceptual learning, we demonstrate that in the elderly, aged 65 to 89 years, the age-related impairment of tactile two-point discrimination can be mitigated substantially. In elderly adults, tactile-acuity thresholds increased to 3.5mm compared with 1.5mm found in young adults, whereas 50-year-old subjects showed intermediate performance. As a result of coactivation, discrimination thresholds of the 80-year-old adults came to match those typically found at an age of 50, demonstrating that age-related decline in tactile performance is not irreversible, but rather subject to considerable restoration by specific stimulation protocols. Interpretation: Because the preservation of sufficient tactile acuity into advanced age is an important prerequisite for the maintenance of autonomous living, we believe that the concept of coactivation might turn out to be beneficial in preserving everyday sensorimotor competence in the elderly through new forms of therapeutic interventions.

Demonstration of cue recruitment: Change in visual appearance by means of Pavlovian conditioning

Abstract: Until half a century ago, associative learning played a fundamental role in theories of perceptual appearance [Berkeley, G. (1709) An Essay Towards a New Theory of Vision (Dublin), 1st Ed.]. But starting in 1955 [Gibson, J. J. & Gibson, E. J. (1955) Psychol. Rev. 62, 32-41], most studies of perceptual learning have not been concerned with association or appearance but rather with improvements in discrimination ability. Here we describe a “cue recruitment” experiment, which is a straightforward adaptation of Pavlov's classical conditioning experiment, that we used to measure changes in visual appearance caused by exposure to novel pairings of signals in visual stimuli. Trainees viewed movies of a rotating wire-frame (Necker) cube. This stimulus is perceptually bistable. On training trials, depth cues (stereo and occlusion) were added to force the perceived direction of rotation. Critically, an additional signal was also added, contingent on rotation direction. Stimuli on test trials contained the new signal but not the depth cues. Over 45 min, two of the three new signals that we tested acquired the ability to bias perceived rotation direction on their own. Results were consistent across the eight trainees in each experiment, and the new cue's effectiveness was long lasting. Whereas most adaptation aftereffects on appearance are opposite in direction to the training stimuli, these effects were positive. An individual new signal can be recruited by the visual system as a cue for the construction of visual appearance. Cue recruitment experiments may prove useful for reexamining of the role of experience in perception.

Brain Changes in the Development of Expertise: Neuroanatomical and Neurophysiological Evidence about Skill-Based Adaptations

Abstract: Introduction As humans acquire skills there are dramatic changes in brain activity that complement the profound changes in processing speed and effort seen in behavioral data. These changes involve learning, developing new representations, strategy shifts, and use of wider cues and approaches. Experts differ from novices in terms of their knowledge, effort, recognition, analysis, strategy, memory use, and monitoring (e.g., see Chi, Chapter 2; Feltovich, Prietula, & Ericsson, Chapter 4). In the last decade, there have be major advances in our ability to noninvasively track human brain activity. There are now over a hundred experiments tracking learning or expert performance. Patterns are beginning to emerge that show that learning and skilled performance produce changes in brain activation – and different types of changes – depending on the brain structure and the nature of the skill being learned. In this chapter, we will review the changes that occur in the brain as skill is acquired. We will detail the anatomy and processes involved. We will provide a brief summary of the methods employed. We will review the nature of learning of skills, resource utilization, and performance of experts. The reader who wishes to learn more details regarding these methods might examine a current introductory chapter (Schneider & Chein, 2003) or current textbooks of cognitive neuroscience (Gazzaniga, Ivry, & Mangun, 2002), brain imaging (Jezzard, Mathews, & Smith, 2001), and cognitive neuroscience modeling (O'Reilly & Munakata, 2000).

Gibson, James J.

Abstract: James J. Gibson (1904–1979) was a leading American scholar and researcher in the field of perception. His dynamic and functional approach radically changed perceptual theories of the time and led to his own theory, the ecological approach to perception. Keywords: perception; adaptation; flow pattern; perceptual systems; ecological approach

Perceptual or motor learning in SRT tasks with complex sequence structures

Abstract: We investigated under which conditions sequence learning in a serial reaction time task can be based on perceptual learning. A replication of the study of Mayr (1996) confirmed perceptual and motor learning when sequences were learned concurrently. However, between-participants manipulations of the motor and perceptual sequences only supported motor learning in cases of more complex deterministic and probabilistic sequence structures. Perceptual learning using a between-participants design could only be established with a simple deterministic sequence structure. The results seem to imply that perceptual learning can be facilitated by a concurrently learned motor sequence. Possibly, concurrent learning releases necessary attentional resources or induces a structured learning condition under which perceptual learning can take place. Alternatively, the underlying mechanism may rely on binding between the perceptual and motor sequences.

Perceptual training improves syllable identification in new and experienced hearing aid users.

Abstract: --We assessed the effects of perceptual training of syllable identification in noise on nonsense syllable test (NST) performance of new (Experiment 1) and experienced (Experiment 2) hearing aid (HA) users with sensorineural hearing loss. In Experiment 1, new HA users were randomly assigned to either immediate training (IT) or delayed training (DT) groups. IT subjects underwent 8 weeks of at-home syllable identification training and in-laboratory testing, whereas DT subjects underwent identical in-laboratory testing without training. Training produced large improvements in syllable identification in IT subjects, whereas spontaneous improvement was minimal in DT subjects. DT subjects then underwent training and showed performance improvements comparable with those of the IT group. Training-related improvement in NST scores significantly exceeded improvements due to amplification. In Experiment 2, experienced HA users received identical training and testing procedures as users in Experiment 1. The experienced users also showed significant training benefit. Training-related improvements generalized to untrained voices and were maintained on retention tests. Perceptual training appears to be a promising tool for improving speech perception in new and experienced HA users. Key words: auditory, hearing aid, hearing loss, learning, masking noise, nonsense syllables, perception, perceptual training, personal computer, phonemes, presbycusis, rehabilitation, speech. INTRODUCTION Progressive high-frequency sensorineural hearing loss (SNHL) alters auditory processing at multiple levels of the auditory system. Most obviously, it alters cochlear function and deprives listeners of high-frequency speech cues that are critical in discriminating consonants [1]. In addition, gradual high-frequency SNHL results in a widespread reorganization of central auditory connections, diminishing high-frequency inputs and enhancing connections from nearby zones with intact cochlear function [2]. Phoneme processing strategies are correspondingly altered, with hearing-impaired subjects depending more on phonetic cues conveyed by low frequencies [3-6]. For example, hearing-impaired subjects rely disproportionately on vowel duration to discriminate voiced and voiceless fricative pairs such as /v/-/f/ and /z/-/s/ [4]. While hearing aids (HAs) can partially compensate for cochlear deficits by amplifying high-frequency sounds, long-standing peripheral hearing loss will also produce neuroplastic alterations within the central auditory system, including changes in synaptic connections and dendritic arborization [7]. While the newly amplified auditory inputs provided by HAs may enhance functional neuroplasticity [8], abnormal synaptic connections will not instantly renormalize. Normalization may be reflected in the gradual perceptual changes occurring during acclimatization [9-11]. However, acclimatization effects are generally small in magnitude and inconsistently obtained [12-15]. This minimal acclimatization benefit suggests that the neuroplastic changes needed to normalize auditory perception often may not occur. In the current study, we investigated the capability of adaptive perceptual training to force reorganization and consequent perceptual improvement in a high-level auditory task: syllable identification. Cortical Plasticity and Perceptual Learning Research over the last decade has revealed extensive neuroplasticity in the auditory system that optimizes neuronal responses to the behaviorally relevant acoustic features present in the environment [16-18]. Changes in cortical organization occur reliably following both selective stimulation and deprivation. For example, explicit exposure to particular sound frequencies can enhance the number of cortical neurons driven by those stimuli and alter neuronal tuning properties and response latencies to favor behaviorally relevant sounds [19]. Environmental enrichment can also sharpen neuronal tuning curves in auditory cortex [20], while noisy environments impair the development of normal tuning [21]. …