视知觉学习的认知与神经机制研究

知觉学习是指由于训练或经验而引起的长期稳定的知觉变化,是一种内隐性的学习。近20年来,视知觉学习的大量研究结果提示大脑皮层的各个区域,甚至包括初级感觉皮层,在成熟之后仍然具有一定的可塑性。该文根据近年来的研究进展,对视知觉学习在大脑的什么地方,什么时候,以何种方式发生等热点问题进行了探讨。研究提示,视知觉学习涉及了包括初级视皮层在内的多个大脑皮层,并且存在一种自上而下的调控机制;视知觉学习可以在不同的时间尺度上发生,快速学习之后将伴随着慢速学习;通过视知觉学习,人们对于复杂物体的表征将从高级皮层区域移向低级皮层区域,任务执行也将趋于自动化     

Qualitative character and sensory representation

Perceptual experience seems to involve distinct intentional and qualitative features. Inasmuch as one can visually perceive that there is a Coke can in front of one, perceptual experience must be intentional. But such experiences seem to differ from paradigmatic intentional states in having introspectible qualitative character. argues that a perceptual experience's qualitative character is determined by intrinsic, nonrepresentational properties. But also argues that perceptual experiences have nonconceptual representational content in addition to conceptual content and nonrepresentational sensational properties. He thus distinguishes between conceptual, nonrepresentational, and nonconceptual but representational aspects of perceptual experience. I will argue that Peacocke posits too much. Contrary to his (1983) arguments, the sensational properties Peacocke claims are nonrepresentational are best construed as representational; they are best explained in terms of their relation to the perceptible properties they enable us to perceive. Since sensational properties are arguably nonconceptual, they are best construed as nonconceptual representational properties. I offer the Homomorphism View of sensory qualities, pioneered by, as a unified account of qualitative character and nonconceptual sensory representation. According to this view, a sensory quality represents a perceptible stimulus property in virtue of resembling and differing from other sensory qualities in ways parallel to the ways the stimulus property resembles and differs from other perceptible properties.     

On scales of sensation: Prolegomena to any future psychophysics that will be able to come forth as science

Sensory scales fall into two classes. Type I scales of sensory intensity can be approximated by metric scaling procedures (magnitude estimation, magnitude production) and nonmetric procedures (conjoint measurement); Type I scales are supported by theoretical consideration of sensory processes. Type II scales of sensory dissimilarity can be approximated by metric scaling procedures (category rating, interval estimation, equisection) and nonmetric procedures (analysis of proximities). The psychophysical functions that relate Type I and Type II scales to their corresponding physical scales are in both cases power functions, but the exponents that govern Type I functions are typically about twice as large. Both Type I scales of sensory intensity and Type II scales of sensory dissimilarity are meaningful measures of perceptual experience, but they are measures of different aspects of perception. The duality of sensory scales helps to explain some apparent contradictions among divergent attempts to validate scales of sensation.     

Late‐ but not early‐onset blindness impairs the development of audio‐haptic multisensory integration

Integrating different senses to reduce sensory uncertainty and increase perceptual precision can have an important compensatory function for individuals with visual impairment and blindness. However, how visual impairment and blindness impact the development of optimal multisensory integration in the remaining senses is currently unknown. Here we first examined how audio‐haptic integration develops and changes across the life span in 92 sighted (blindfolded) individuals between 7 and 70 years of age. We used a child‐friendly task in which participants had to discriminate different object sizes by touching them and/or listening to them. We assessed whether audio‐haptic performance resulted in a reduction of perceptual uncertainty compared to auditory‐only and haptic‐only performance as predicted by maximum‐likelihood estimation model. We then compared how this ability develops in 28 children and adults with different levels of visual experience, focussing on low‐vision individuals and blind individuals that lost their sight at different ages during development. Our results show that in sighted individuals, adult‐like audio‐haptic integration develops around 13–15 years of age, and remains stable until late adulthood. While early‐blind individuals, even at the youngest ages, integrate audio‐haptic information in an optimal fashion, late‐blind individuals do not. Optimal integration in low‐vision individuals follows a similar developmental trajectory as that of sighted individuals. These findings demonstrate that visual experience is not necessary for optimal audio‐haptic integration to emerge, but that consistency of sensory information across development is key for the functional outcome of optimal multisensory integration.     

The epistemic force of perceptual experience

What is the metaphysical nature of perceptual experience? What evidence does experience provide us with? These questions are typically addressed in isolation. In order to make progress in answering both questions, perceptual experience needs to be studied in an integrated manner. I develop a unified account of the phenomenological and epistemological role of perceptual experience, by arguing that sensory states provide perceptual evidence due to their metaphysical structure. More specifically, I argue that sensory states are individuated by the perceptual capacities employed and that there is an asymmetric dependence between their employment in perception and their employment in hallucination and illusion. Due to this asymmetric dependence, sensory states provide us with evidence.     

Modality-specific interference between action planning and perceptual processing

This paper reports a study which examined an interaction between action planning and processing of perceptual information in two different sensory modalities. In line with the idea that action planning consists in representing the action’s sensory outcomes, it was assumed that different types of actions should be coupled with different modalities. A visual and auditory oddball paradigm was combined with two types of actions: pointing and knocking (unrelated to the perceptual task). Results showed an interactive effect between the action type and the sensory modality of the oddballs, with impaired detection of auditory oddballs for knocking (congruent) action, as compared to a pointing (incongruent) action. These findings reveal that action planning can interact with modality-specific perceptual processing and that preparing an action presumably binds the respective perceptual features with an action plan, thereby making these features less available for other tasks.     

Vision merges with touch in a purely tactile discrimination

To construct a coherent percept of the world, the brain continuously combines information across multiple sensory modalities. Simple stimuli from different modalities are usually assumed to be processed in distinct brain areas. However, there is growing evidence that simultaneous stimulation of multiple modalities can influence the activity in unimodal sensory areas and improve or impair performance in unimodal tasks. Do these effects reflect a genuine cross-modal integration of sensory signals, or are they due to changes in the perceiver's ability to locate the stimulus in time and space? We used a behavioral measure to differentiate between these explanations. Our results demonstrate that, under certain circumstances, a noninformative flash of light can have facilitative or detrimental effects on a simple tactile discrimination. The effect of the visual flash mimics that produced by a constant tactile pedestal stimulus. These findings reveal that sensory signals from different modalities can be integrated, even for perceptual judgments within a single modality.     

Controlling for dilution while manipulating load: Perceptual and sensory limitations are just two aspects of task difficulty

Lavie and de Fockert (2003) proposed that perceptual load and sensory limitations reflect two distinct mechanisms producing opposite effects: Perceptual load eliminates distractor interference, whereas sensory limitations enhance it. Tsal and Benoni (2010a) suggested that these results may have been due to the confounding effect of dilution--that is, to the presence (perceptual load) or absence (sensory load) of neutral items capable of diluting distractor interference. In the present study, we jointly manipulated dilution with perceptual load and with sensory degradation. The results show that, with both perceptual and sensory manipulations, the presence of diluting items eliminates distractor interference, whereas controlling for dilution increases distractor interference. We therefore conclude that perceptual and sensory limitations are just two aspects of task difficulty.     

通道估计可靠性先验知识在早期的知觉加工阶段影响多感觉信息整合

统计最优化理论认为, 在多感觉信息整合的过程中, 大脑是以加权平均的方式将多个感觉通道的信息整合为统一的感觉信息, 通道信息的利用权重根据各通道信息的可靠性来确定。近期的几个行为研究结果则显示, 有关通道估计可靠性的先验知识同样能够影响通道信息在整合过程中的利用权重。然而, 这些研究结果不能确定先验知识对多感觉信息整合的影响是发生在认知加工的感知觉阶段还是决策阶段。当前研究致力于对此问题进行探讨。实验通过赋予两种颜色字母不同的视、听一致概率(高概率、低概率), 测量并分析被试在各概率水平下对视听一致刺激的反应时。实验数据显示不同的视听一致概率能够调制对视听一致刺激的反应时。该结果揭示通道估计可靠性先验知识在早期的知觉加工阶段影响多感觉信息整合。     

Effet de l’action motrice sur les asynchronies perceptives

In agreement with the hypothesis of differential treatment of the intrinsic (color, shape, category…) and extrinsic (position, orientation…) visual characteristics along the ventral and dorsal pathways of the visual system (Milner & Goodale, 1995), the study of temporal order judgment (TOJ) of the variation of two visual attributes highlighted the perceptual asynchrony even though these changes occur synchronously. In this context, we investigated the role of action in the perception of perceptual asynchrony, especially the effect of a reaching movement on the TOJ of position and color changes of a target occurring at different times of movement execution. In the absence of voluntary action, the point of subjective simultaneity (PSS) shows that the color changes must occurr 46.6 ms before the change of position to give rise to a synchronous perception of these two changes. Performing a reaching movement reduced significantly the PSS (12.4 ms), but only if the changes occur near movement end-point. If changes occur during movement execution, the PSS (40.2 ms) was not different from that obtained in the perceptual condition. These results suggest that endogenous signals associated with voluntary motor action contribute to the reduction of perceptual asynchrony in relation to the goal of the action. We discuss the possibility that, in the context of the action, the motor system contributes to the binding of objects sensory attributes as well as to the sense of agency.     

Selective attention and the acquisition of new phonetic categories

A class of selective attention models often applied to speech perception is used to study effects of training on the perception of an unfamiliar phonetic contrast. Attention-to-dimension (A2D) models of perceptual learning assume that the dimensions that structure listeners' perceptual space are constant and that learning involves only the reweighting of existing dimensions to emphasize or de-emphasize different sensory dimensions. Multidimensional scaling is used to identify the acoustic-phonetic dimensions listeners use before and after training to recognize the 3 classes of Korean stop consonants. Results suggest that A2D models can account for some observed restructuring of listeners' perceptual space, but listeners also show evidence of directing attention to a previously unattended dimension of phonetic contrast.     

Reply to Kurth,Crosby, and Basse’s review of Emotions,Values, and Agency

In this reply, I argue that the worries raised by Kurth and this coauthors are not fatal for the perceptual theory of emotions. A first point to keep in mind in discussing the analogy argument in favor of that account is that what counts is the overall balance of similarities and differences, given their respective weight. In any case, I argue that none of the alleged differences between sensory perceptual experiences and emotions are such as to rule out that emotions are a kind of perceptual experience which can confer epistemic justification of our evaluative beliefs. Finally, I suggest that the perceptual theory is in a position to nicely capture what happens when we disagree about evaluative issues.     

Dreaming: cognitive processes during cortical activation and high afferent thresholds

The concepts of nonlocal, or distributed, cortical and cognitive activation are examined for their usefulness in describing the relations between sleep and waking neurocognitive processes. Changes in the pattern of distributed activation and inhibition of selected portions of sensory, cognitive, and motor decision modules account for the differences in imagery and thought across sleep and waking states in comparable environments. The massive inhibition of sensory and proprioceptive input to perceptual modules in Stage 1 REM sleep leaves the perceptual and cognitive modules, by default, with their own output as their sole input. Given this constraint, the activation of portions of the cortical structures that execute waking perceptual, cognitive and motor responses is necessary and sufficient to produce the imagery and thought of dreaming sleep. Connectionist models are introduced so that neurophysiological and cognitive concepts of distributed and local activation and inhibition can be translated into a common language, and in so doing, are used to simulate several processes fundamental to the production of imaginal thought and dreaming.     

Crossmodal identification

Everyday experience involves the continuous integration of information from multiple sensory inputs. Such crossmodal interactions are advantageous since the combined action of different sensory cues can provide information unavailable from their individual operation, reducing perceptual ambiguity and enhancing responsiveness. The behavioural consequences of such multimodal processes and their putative neural mechanisms have been investigated extensively with respect to orienting behaviour and, to a lesser extent, the crossmodal coordination of spatial attention. These operations are concerned mainly with the determination of stimulus location. However, information from different sensory streams can also be combined to assist stimulus identification. Psychophysical and physiological data indicate that these two crossmodal processes are subject to different temporal and spatial constraints both at the behavioural and neuronal level and involve the participation of distinct neural substrates. Here we review the evidence for such a dissociation and discuss recent neurophysiological, neuroanatomical and neuroimaging findings that shed light on the mechanisms underlying crossmodal identification, with specific reference to audio-visual speech perception.     

Perception from the First‐Person Perspective

This paper develops a view of the content of perceptual states that reflects the cognitive significance those states have for the subject. Perhaps the most important datum for such a theory is the intuition that experiences are ‘transparent’, an intuition promoted by philosophers as diverse as Sartre and Dretske. This paper distinguishes several different transparency theses, and considers which ones are truly supported by the phenomenological data. It is argued that the only thesis supported by the data is much weaker than those typically considered in the literature, and has no obvious implications for the existence of sensory intermediaries. It does, however, have implications for the content of perceptual experience. It is argued that combining the first personal project with the transparency intuition yields an error theory of perception. The counterintuitive implications of this error theory are mitigated, however, by an account of perceptual beliefs which allows for them to be true even if the perceptual states are non‐veridical.     

Developmental Improvements in Perceptual Restoration: Can Young Children Reconstruct Missing Sounds in Noisy Environments?

Young children are frequently exposed to sounds such as speech and music in noisy listening conditions, which have the potential to disrupt their learning. Missing input that is masked by louder sounds can, under the right conditions, be ‘filled in’ by the perceptual system using a process known as perceptual restoration. This experiment compared the ability of 4‐ to 6‐year‐old children, 9‐ to 11‐year‐old children and adults to complete a melody identification task using perceptual restoration. Melodies were presented either intact (complete input), with noise‐filled gaps (partial input; perceptual restoration can occur) or with silence‐filled gaps (partial input; perceptual restoration cannot occur). All age groups could use perceptual restoration to help them interpret partial input, yet perception was the most detrimentally affected by the presentation of partial input for the youngest children. This implies that they might have more difficulty perceiving sounds in noisy environments than older children or adults. Young children had particular difficulty using partial input for identification under conditions where perceptual restoration could not occur. These findings suggest that perceptual restoration is a crucial mechanism in young children, where processes that fill in missing sensory input represent an important part of the way meaning is extracted from a complex sensory world. Copyright © 2011 John Wiley & Sons, Ltd.     

Perceptual hysteresis as a marker of perceptual inflexibility in schizophrenia

People with schizophrenia are known to exhibit difficulties in the updating of their current belief states even in the light of disconfirmatory evidence. In the present study we tested the hypothesis that people with schizophrenia could also manifest perceptual inflexibility, or difficulties in the updating of their current sensory states. The presence of perceptual inflexibility might contribute both to the patients’ altered perception of reality and the formation of some delusions as well as to their social cognition deficits. Here, we addressed this issue with a protocol of auditory hysteresis, a direct measure of sensory persistence, on a population of stabilized antipsychotic-treated schizophrenia patients and a sample of control subjects. Trials consisted of emotional signals (i.e., screams) and neutral signals (i.e., spectrally-rotated versions of the emotional stimuli) progressively emerging from white noise – Ascending Sequences – or progressively fading away in white noise – Descending Sequences. Results showed that patients presented significantly stronger hysteresis effects than control subjects, as evidenced by a higher rate of perceptual reports in Descending Sequences. The present study thus provides direct evidence of perceptual inflexibility in schizophrenia.     

0 + 1 > 1: How adding noninformative sound improves performance on a visual task

It is well known that the nervous system combines information from different cues within and across sensory modalities to improve performance on perceptual tasks. In this article, we present results showing that in a visual motion-detection task, concurrent auditory motion stimuli improve accuracy even when they do not provide any useful information for the task. When participants judged which of two stimulus intervals contained visual coherent motion, the addition of identical moving sounds to both intervals improved accuracy. However, this enhancement occurred only with sounds that moved in the same direction as the visual motion. Therefore, it appears that the observed benefit of auditory stimulation is due to auditory-visual interactions at a sensory level. Thus, auditory and visual motion-processing pathways interact at a sensory-representation level in addition to the level at which perceptual estimates are combined.     

". . . On the Basis of Velocity Clues Alone": Some Perceptual Themes 1946-1996

Three factors that have transformed perceptual research in the last fifty years are the digital computer, single-unit electrophysiology, and molecular biology. Amongst the developments in which members of the Experimental Psychology Society have been central are: the recognition of the role of optic flow in spatial vision; the demonstration that our perceptual systems contain parallel pathways extracting different information from the sensory array; the identification of specific detectors that can be selectively adapted in psychophysical experiments; and the transfer of the concepts of fourier analysis from audition to vision. The history of Opponent Process Theory offers an example where experimental psychologists have been misled by too simple an interpretation of physiological recordings.