Showing papers on "Perceptual learning published in 2009"

Learning sculpts the spontaneous activity of the resting human brain

Abstract: The brain is not a passive sensory-motor analyzer driven by environmental stimuli, but actively maintains ongoing representations that may be involved in the coding of expected sensory stimuli, prospective motor responses, and prior experience. Spontaneous cortical activity has been proposed to play an important part in maintaining these ongoing, internal representations, although its functional role is not well understood. One spontaneous signal being intensely investigated in the human brain is the interregional temporal correlation of the blood-oxygen level-dependent (BOLD) signal recorded at rest by functional MRI (functional connectivity-by-MRI, fcMRI, or BOLD connectivity). This signal is intrinsic and coherent within a number of distributed networks whose topography closely resembles that of functional networks recruited during tasks. While it is apparent that fcMRI networks reflect anatomical connectivity, it is less clear whether they have any dynamic functional importance. Here, we demonstrate that visual perceptual learning, an example of adult neural plasticity, modifies the resting covariance structure of spontaneous activity between networks engaged by the task. Specifically, after intense training on a shape-identification task constrained to one visual quadrant, resting BOLD functional connectivity and directed mutual interaction between trained visual cortex and frontal-parietal areas involved in the control of spatial attention were significantly modified. Critically, these changes correlated with the degree of perceptual learning. We conclude that functional connectivity serves a dynamic role in brain function, supporting the consolidation of previous experience.

Reinforcement learning can account for associative and perceptual learning on a visual-decision task

Abstract: We recently showed that improved perceptual performance on a visual motion direction-discrimination task corresponds to changes in how an unmodified sensory representation in the brain is interpreted to form a decision that guides behavior. Here we found that these changes can be accounted for using a reinforcement-learning rule to shape functional connectivity between the sensory and decision neurons. We modeled performance on the basis of the readout of simulated responses of direction-selective sensory neurons in the middle temporal area (MT) of monkey cortex. A reward prediction error guided changes in connections between these sensory neurons and the decision process, first establishing the association between motion direction and response direction, and then gradually improving perceptual sensitivity by selectively strengthening the connections from the most sensitive neurons in the sensory population. The results suggest a common, feedback-driven mechanism for some forms of associative and perceptual learning.

Perceptual Training Narrows the Temporal Window of Multisensory Binding

Abstract: The brain’s ability to bind incoming auditory and visual stimuli depends critically on the temporal structure of this information. Specifically, there exists a temporal window of audiovisual integration within which stimuli are highly likely to be bound together and perceived as part of the same environmental event. Several studies have described the temporal bounds of this window, but few have investigated its malleability. Here, the plasticity in the size of this temporal window was investigated using a perceptual learning paradigm in which participants were given feedback during a two-alternative forced-choice (2-AFC) audiovisual simultaneity judgment task. Training resulted in a marked (i.e., approximately 40%) narrowing in the size of the window. To rule out the possibility that this narrowing was the result of changes in cognitive biases, a second experiment employing a two-interval forced choice (2-IFC) paradigm was undertaken during which participants were instructed to identify a simultaneously-presented audiovisual pair presented within one of two intervals. The 2-IFC paradigm resulted in a narrowing that was similar in both degree and dynamics to that using the 2-AFC approach. Together, these results illustrate that different methods of multisensory perceptual training can result in substantial alterations in the circuits underlying the perception of audiovisual simultaneity. These findings suggest a high degree of flexibility in multisensory temporal processing and have important implications for interventional strategies that may be used to ameliorate clinical conditions (e.g., autism, dyslexia) in which multisensory temporal function may be impaired.

Olfactory perceptual learning requires adult neurogenesis

Abstract: Perceptual learning is required for olfactory function to adapt appropriately to changing odor environments. We here show that newborn neurons in the olfactory bulb are not only involved in, but necessary for, olfactory perceptual learning. First, the discrimination of perceptually similar odorants improves in mice after repeated exposure to the odorants. Second, this improved discrimination is accompanied by an elevated survival rate of newborn inhibitory neurons, preferentially involved in processing of the learned odor, within the olfactory bulb. Finally, blocking neurogenesis before and during the odorant exposure period prevents this learned improvement in discrimination. Olfactory perceptual learning is thus mediated by the reinforcement of functional inhibition in the olfactory bulb by adult neurogenesis.

Task precision at transfer determines specificity of perceptual learning.

Abstract: Perceptual learning, the improvement in performance with practice, reflects plasticity in the adult visual system. We challenge a standard claim that specificity of perceptual learning depends on task difficulty during training, instead showing that specificity, or conversely transfer, is primarily controlled by the precision demands (i.e., orientation difference) of the transfer task. Thus, for an orientation discrimination task, transfer of performance improvement is observed in low-precision transfer tasks, while specificity of performance improvement is observed in high-precision transfer tasks, regardless of the precision of initial training. The nature of specificity places important constraints on mechanisms of transfer in visual learning. These results contribute to understanding generalization of practiced improvements that may be key to the development of expertise and for applications in remediation.

Reverse hierarchies and sensory learning

Abstract: Revealing the relationships between perceptual representations in the brain and mechanisms of adult perceptual learning is of great importance, potentially leading to significantly improved training techniques both for improving skills in the general population and for ameliorating deficits in special populations. In this review, we summarize the essentials of reverse hierarchy theory for perceptual learning in the visual and auditory modalities and describe the theory's implications for designing improved training procedures, for a variety of goals and populations.

Narrowing of intersensory speech perception in infancy

Abstract: The conventional view is that perceptual/cognitive development is an incremental process of acquisition. Several striking findings have revealed, however, that the sensitivity to non-native languages, faces, vocalizations, and music that is present early in life declines as infants acquire experience with native perceptual inputs. In the language domain, the decline in sensitivity is reflected in a process of perceptual narrowing that is thought to play a critical role during the acquisition of a native-language phonological system. Here, we provide evidence that such a decline also occurs in infant response to multisensory speech. We found that infant intersensory response to a non-native phonetic contrast narrows between 6 and 11 months of age, suggesting that the perceptual system becomes increasingly more tuned to key native-language audiovisual correspondences. Our findings lend support to the notion that perceptual narrowing is a domain-general as well as a pan-sensory developmental process.

Perceptual Other-Race Training Reduces Implicit Racial Bias

Abstract: Background Implicit racial bias denotes socio-cognitive attitudes towards other-race groups that are exempt from conscious awareness. In parallel, other-race faces are more difficult to differentiate relative to own-race faces – the “Other-Race Effect.” To examine the relationship between these two biases, we trained Caucasian subjects to better individuate other-race faces and measured implicit racial bias for those faces both before and after training. Methodology/Principal Findings Two groups of Caucasian subjects were exposed equally to the same African American faces in a training protocol run over 5 sessions. In the individuation condition, subjects learned to discriminate between African American faces. In the categorization condition, subjects learned to categorize faces as African American or not. For both conditions, both pre- and post-training we measured the Other-Race Effect using old-new recognition and implicit racial biases using a novel implicit social measure – the “Affective Lexical Priming Score” (ALPS). Subjects in the individuation condition, but not in the categorization condition, showed improved discrimination of African American faces with training. Concomitantly, subjects in the individuation condition, but not the categorization condition, showed a reduction in their ALPS. Critically, for the individuation condition only, the degree to which an individual subject's ALPS decreased was significantly correlated with the degree of improvement that subject showed in their ability to differentiate African American faces. Conclusions/Significance Our results establish a causal link between the Other-Race Effect and implicit racial bias. We demonstrate that training that ameliorates the perceptual Other-Race Effect also reduces socio-cognitive implicit racial bias. These findings suggest that implicit racial biases are multifaceted, and include malleable perceptual skills that can be modified with relatively little training.

Perceptual learning and adult cortical plasticity.

Abstract: The visual cortex retains the capacity for experience-dependent changes, or plasticity, of cortical function and cortical circuitry, throughout life. These changes constitute the mechanism of perceptual learning in normal visual experience and in recovery of function after CNS damage. Such plasticity can be seen at multiple stages in the visual pathway, including primary visual cortex. The manifestation of the functional changes associated with perceptual learning involve both long term modification of cortical circuits during the course of learning, and short term dynamics in the functional properties of cortical neurons. These dynamics are subject to top-down influences of attention, expectation and perceptual task. As a consequence, each cortical area is an adaptive processor, altering its function in accordance to immediate perceptual demands.

Perceptual learning of systematic variation in Spanish-accented speech

Abstract: Spoken language is characterized by an enormous amount of variability in how linguistic segments are realized. In order to investigate how speech perceptual processes accommodate to multiple sources of variation, adult native speakers of American English were trained with English words or sentences produced by six Spanish-accented talkers. At test, listeners transcribed utterances produced by six familiar or unfamiliar Spanish-accented talkers. With only brief exposure, listeners perceptually adapted to accent-general regularities in spoken language, generalizing to novel accented words and sentences produced by unfamiliar accented speakers. Acoustic properties of vowel production and their relation to identification performance were assessed to determine if the English listeners were sensitive to systematic variation in the realization of accented vowels. Vowels that showed the most improvement after Spanish-accented training were distinct from nearby vowels in terms of their acoustic characteristics. These findings suggest that the speech perceptual system dynamically adjusts to the acoustic consequences of changes in talker’s voice and accent.

Improving the performance of the amblyopic visual system

Abstract: Experience-dependent plasticity is closely linked with the development of sensory function; however, there is also growing evidence for plasticity in the adult visual system. This review re-examines the notion of a sensitive period for the treatment of amblyopia in the light of recent experimental and clinical evidence for neural plasticity. One recently proposed method for improving the effectiveness and efficiency of treatment that has received considerable attention is ‘perceptual learning’. Specifically, both children and adults with amblyopia can improve their perceptual performance through extensive practice on a challenging visual task. The results suggest that perceptual learning may be effective in improving a range of visual performance and, importantly, the improvements may transfer to visual acuity. Recent studies have sought to explore the limits and time course of perceptual learning as an adjunct to occlusion and to investigate the neural mechanisms underlying the visual improvement. These findings, along with the results of new clinical trials, suggest that it might be time to reconsider our notions about neural plasticity in amblyopia.

Perception and Basic Beliefs: Zombies, Modules, and the Problem of the External World

Abstract: Abbreviations Chapter 1: External Object Foundationalism 1.1The Problem of the External World 1.2 Metaphysical and Epistemological Direct Realisms 1.3 Basic Beliefs Chapter 2: Doxastic and Nondoxastic Theories 2.1 Evidential and Nonevidential Justifiers 2.2 The Supervenience Argument 2.3 Doxasticism and Nondoxasticism 2.4 Doxastic Theories Chapter 3: Experientialist Theories: 3.1 Sensation and Perception 3.2 Sensations as Grounds 3.2.1 Sensationless Perception 3.2.2 The Sensation/perception Gap and Collateral Information 3.2.3 Problems Concerning Basing 3.2.4 SE and the Content of Sensations 3.3 Percepts as Grounds 3.3.1 In Search of the Percept 3.3.2 Percepts and Beliefs 3.3.3 The Zombies Return 3.4 The Belief Principle 3.5 Experiential States as Nonevidential Justifiers 3.6 Intuitive Resistance 3.7 Recapitulation Chapter 4: Perceptual Systems and Perceptual Beliefs 4.1 Perceptual Systems 4.1.1 Cognitive Systems/Modules 4.1.2 Perceptual Modules 4.2 The Plausibility of the Perceptual System Theory 4.2.1 The "Grain Size" of Perceptual Beliefs 4.2.2 Perception and Ungrounded Justified Belief 4.2.3 Perceptual Learning and Nonexperiential 'Looks' 4.2.4 Percept Experientialism Revisited 4.3 Perceptual Beliefs and Basic Beliefs Chapter 5: Perception, Clairvoyance, and Reliability 5.1 Simple Reliabilism and the Norman/Truetemp Objections 5.2 Clairvoyance and Basicality 5.2.1 Underspecification and the "Clairvoyance Challenge" 5.2.2 Perception and Other Cognitive Abilities 5.2.3 "Meta-Incoherence" 5.3 Reliability and Basicality 5.3.1Clairvoyance and Defeat 5.3.2 Experientialist Reliabilism 5.3.3 Early Reliabilism 5.3.4 Teleological Reliabilism Chapter 6: Basic Beliefs 6.1 The Delineation Problem 6.1.1 The Desiderata 6.1.2 A Systems Theory of Basicality 6.1.3 Counterexamples and Replies 6.2 Intuitions and Beyond 6.2.1 Descriptive and Normative Epistemology 6.2.2 Cognitive Science and Basicality 6.2.3 Illustration: Why My Philosophy is More God-Friendly than Plantinga's 6.2.4 Reflective Equilibrium and Etiological Constraints Chapter 7: Basic and Nonbasic Beliefs in a Reliabilist Epistemology 7.1Toward a Theory of Justification 7.1.1 Evidential Justification 7.1.2 Defeat 7.1.3 Outline of a Theory 7.2 Internalism and Externalism 7.3 The Problem(s) of the External World References Index

Perceptual Learning Modules in Mathematics: Enhancing Students' Pattern Recognition, Structure Extraction, and Fluency.

Abstract: Learning in educational settings emphasizes declarative and procedural knowledge. Studies of expertise, however, point to other crucial components of learning, especially improvements produced by experience in the extraction of information: perceptual learning (PL). We suggest that such improvements characterize both simple sensory and complex cognitive, even symbolic, tasks through common processes of discovery and selection. We apply these ideas in the form of perceptual learning modules (PLMs) to mathematics learning. We tested three PLMs, each emphasizing different aspects of complex task performance, in middle and high school mathematics. In the MultiRep PLM, practice in matching function information across multiple representations improved students’ abilities to generate correct graphs and equations from word problems. In the Algebraic Transformations PLM, practice in seeing equation structure across transformations (but not solving equations) led to dramatic improvements in the speed of equation solving. In the Linear Measurement PLM, interactive trials involving extraction of information about units and lengths produced successful transfer to novel measurement problems and fraction problem solving. Taken together, these results suggest (a) that PL techniques have the potential to address crucial, neglected dimensions of learning, including discovery and fluent processing of relations; (b) PL effects apply even to complex tasks that involve symbolic processing; and (c) appropriately designed PL technology can produce rapid and enduring advances in learning.

Auditory plasticity and speech motor learning

Abstract: Is plasticity in sensory and motor systems linked? Here, in the context of speech motor learning and perception, we test the idea sensory function is modified by motor learning and, in particular, that speech motor learning affects a speaker's auditory map. We assessed speech motor learning by using a robotic device that displaced the jaw and selectively altered somatosensory feedback during speech. We found that with practice speakers progressively corrected for the mechanical perturbation and after motor learning they also showed systematic changes in their perceptual classification of speech sounds. The perceptual shift was tied to motor learning. Individuals that displayed greater amounts of learning also showed greater perceptual change. Perceptual change was not observed in control subjects that produced the same movements, but in the absence of a force field, nor in subjects that experienced the force field but failed to adapt to the mechanical load. The perceptual effects observed here indicate the involvement of the somatosensory system in the neural processing of speech sounds and suggest that speech motor learning results in changes to auditory perceptual function.

Spatial Learning and Computer Simulations in Science

Abstract: Interactive simulations are entering mainstream science education. Their effects on cognition and learning are often framed by the legacy of information processing, which emphasized amodal problem solving and conceptual organization. In contrast, this paper reviews simulations from the vantage of research on perception and spatial learning, because most simulations take a spatial format and the pedagogical intent is to promote learning. Four learning effects help clarify the positive and negative aspects of current simulation designs: picture superiority, noticing, structuring, and tuning.

A Generalized Mechanism for Perception of Pitch Patterns

Abstract: Surviving in a complex and changeable environment relies on the ability to extract probable recurring patterns. Here we report a neurophysiological mechanism for rapid probabilistic learning of a new system of music. Participants listened to different combinations of tones from a previously unheard system of pitches based on the Bohlen-Pierce scale, with chord progressions that form 3:1 ratios in frequency, notably different from 2:1 frequency ratios in existing musical systems. Event-related brain potentials elicited by improbable sounds in the new music system showed emergence over a 1 h period of physiological signatures known to index sound expectation in standard Western music. These indices of expectation learning were eliminated when sound patterns were played equiprobably, and covaried with individual behavioral differences in learning. These results demonstrate that humans use a generalized probability-based perceptual learning mechanism to process novel sound patterns in music.