Impaired categorical perception of lexical tones in Mandarin-speaking congenital amusics

The degree to which cognitive resources are shared in the processing of musical pitch and lexical tones remains uncertain. Testing Mandarin amusics on their categorical perception of Mandarin lexical tones may provide insight into this issue. In the present study, a group of 15 amusic Mandarin speakers identified and discriminated Mandarin tones presented as continua in separate blocks. The tonal continua employed were from a high-level tone to a mid-rising tone and from a high-level tone to a high-falling tone. The two tonal continua were made in the contexts of natural speech and of nonlinguistic analogues. In contrast to the controls, the participants with amusia showed no improvement for discrimination pairs that crossed the classification boundary for either speech or nonlinguistic analogues, indicating a lack of categorical perception. The lack of categorical perception of Mandarin tones in the amusic group shows that the pitch deficits in amusics may be domain-general, and this suggests that the processing of musical pitch and lexical tones may share certain cognitive resources and/or processes (Patel 2003, 2008, 2012).     

音乐训练对4~5岁幼儿普通话声调范畴感知能力的影响

已有研究表明, 音乐训练能提高成人对普通话声调范畴感知的能力, 此种训练能否增强幼儿对声调范畴感知的能力?训练效果是否受到训练时间长短的影响?本研究对幼儿园4~5岁幼儿进行音乐训练, 共40人, 分成音乐组和控制组, 每组各20人, 追踪考察音乐训练和训练时间长短对幼儿声调范畴感知能力提升的影响。实验采用前测-中测-后测设计, 对音乐组开展每周3次, 每次30分钟, 以小钟琴演奏为主的音乐训练; 控制组不进行任何有组织的训练活动。结果发现, 12个月音乐训练提升了幼儿对声调范畴感知的程度, 表现为音乐组幼儿范畴边界宽度显著小于控制组, 而训练6个月时, 该优势并不显著。此外, 12个月音乐训练还加强了幼儿区分范畴内刺激声学差异的敏感性, 而对范畴间刺激的区分能力无显著提高。本研究结果支持了音乐学习的歌剧理论(OPERA), 音乐训练具有跨域迁移作用, 可提升4~5岁幼儿对普通话声调范畴感知的能力, 但只有长期持续的训练才可能真正提高幼儿的音高精细化加工水平。     

The ABCs of categorical perception

Studies of speech perception first revealed a surprising discontinuity in the way in which stimulus values on a physical continuum are perceived. Data which demonstrate the effect in nonspeech modes have challenged the contention that categorical perception is a hallmark of the speech mode, but the psychophysical models that have been proposed have not resolved the issues raised by empirical findings. This study provides data from judgments of four sensory continua, two visual and two tactual-kinesthetic, which show that the adaptation level for a set of stimuli serves as a category boundary whether stimuli on the continuum differ by linear or logarithmic increments. For all sensory continua studied, discrimination of stimuli belonging to different perceptual categories was more accurate than discrimination of stimuli belonging to the same perceptual category. Moreover, shifts in the adaptation level produced shifts in the location of the category boundary. The concept of Adaptation-level Based Categorization (ABC) provides a unified account of judgmental processes in categorical perception without recourse to post hoc constructs such as implicit anchors or external referents.     

Neural network models of categorical perception

Studies of the categorical perception (CP) of sensory continua have a long and rich history in psychophysics. In 1977, Macmillan, Kaplan, and Creelman introduced the use of signal detection theory to CP studies. Anderson and colleagues simultaneously proposed the first neural model for CP, yet this line of research has been less well explored. In this paper, we assess the ability of neural-network models of CP to predict the psychophysical performance of real observers with speech sounds and artificial/novel stimuli. We show that a variety of neural mechanisms are capable of generating the characteristics of CP. Hence, CP may not be a special model of perception but an emergent property of any sufficiently powerful general learning system.     

Dispersion in models of categorical perception

A signal detection theory model of auditory discrimination with a nonlinear mapping from stimulus continuum to perceptual continuum can account for the enhanced discrimination at the category boundary found in categorical perception. Properties of this transformation are specified by a unimodal “dispersion function”. Furthermore, it is shown that a system consisting of two acoustic feature detectors with an associated decision function is also a dispersive system, which models categorical perception of a stimulus continuum as well as boundary shifts under adaptation. The effect of detector adaptation on discrimination is discussed in view of three different types of decision variable and different types of detector noise.     

Some experiments relating to the perception of complex tones

Pattern recognition models for the perception of complex tones assume that the pitch of a complex tone is derived from more primary sensations, such as the pitches of the individual partials. Thus a complex tone will only have a well-defined pitch when at least one partial in the complex is separately perceptible. Models based on time-interval measurements, on the other hand, require an interaction of the original components, so that the periodicity of the input waveform is preserved. In Experiment I the relative intensity of a “target” tone, necessary for its identification in the presence of either one or two “masking” tones, was determined, over a range of frequencies. This intensity changes abruptly at around 5 kHz, a result consistent with the idea that the pitches of pure tones are determined by temporal mechanisms for frequencies up to 5 kHz, and by place mechanisms for frequencies above this. In Experiments II and III the audibility of the partials in a multi-tone complex was measured as a function of their frequency separation and compared with the range of conditions over which a complex stimulus produced a clear pitch sensation, using the same set of subjects in each experiment. It was found that under some conditions the complex had a well-defined pitch when none of the individual partials was separately audible. This is contrary to the predictions from the pattern recognition models. The effects of masking noise in the frequency region below the complex, and the results of individual subjects, also did not conform with the predictions from these models. Such models are not ruled out, however, for low harmonic numbers, or for stimuli containing only a small number of partials.     

Neurophysiological evidence for categorical perception of color

The aim of this investigation was to examine the time course and the relative contributions of perceptual and post-perceptual processes to categorical perception (CP) of color. A visual oddball task was used with standard and deviant stimuli from same (within-category) or different (between-category) categories, with chromatic separations for within- and between-category stimuli equated in Munsell Hue. CP was found on a behavioral version of the task, with faster RTs and greater accuracy for between- compared to within-category stimuli. On a neurophysiological version of the task, event-related potentials (ERPs) showed earlier latencies for P1 and N1 components at posterior locations to between- relative to within-category deviants, providing novel evidence for early perceptual processes on color CP. Enhanced P2 and P3 waves were also found for between- compared to within-category stimuli, indicating a role for later post-perceptual processes.     

Positional effects in the lexical retuning of speech perception

Listeners use lexical knowledge to adjust to speakers’ idiosyncratic pronunciations. Dutch listeners learn to interpret an ambiguous sound between /s/ and /f/ as /f/ if they hear it word-finally in Dutch words normally ending in /f/, but as /s/ if they hear it in normally /s/-final words. Here, we examined two positional effects in lexically guided retuning. In Experiment 1, ambiguous sounds during exposure always appeared in word-initial position (replacing the first sounds of /f/- or /s/-initial words). No retuning was found. In Experiment 2, the same ambiguous sounds always appeared word-finally during exposure. Here, retuning was found. Lexically guided perceptual learning thus appears to emerge reliably only when lexical knowledge is available as the to-be-tuned segment is initially being processed. Under these conditions, however, lexically guided retuning was position independent: It generalized across syllabic positions. Lexical retuning can thus benefit future recognition of particular sounds wherever they appear in words.     

Neuroelectrical correlates of categorical speech perception in adults

Auditory evoked potentials were recorded from the left and right hemispheres of 16 adults during a phoneme identification task. The use of multivariate statistics enabled researchers to identify a number of cortical processes related to categorical speech perception which were common to both hemispheres, as well as several which disinguished between the two hemispheres.     

On the (non)persuasive power of a brain image

The persuasive power of brain images has captivated scholars in many disciplines. Like others, we too were intrigued by the finding that a brain image makes accompanying information more credible (McCabe & Castel in Cognition 107:343-352, 2008). But when our attempts to build on this effect failed, we instead ran a series of systematic replications of the original study—comprising 10 experiments and nearly 2,000 subjects. When we combined the original data with ours in a meta-analysis, we arrived at a more precise estimate of the effect, determining that a brain image exerted little to no influence. The persistent meme of the influential brain image should be viewed with a critical eye.     

Context sensitivity and invariance in perception of octave-ambiguous tones

Three experiments investigated the influence of unambiguous (UA) context tones on the perception of octave-ambiguous (OA) tones. In Experiment 1, pairs of OA tones spanning a tritone interval were preceded by pairs of UA tones instantiating a rising or falling interval between the same pitch classes. Despite the inherent ambiguity of OA tritone pairs, most participants showed little or no priming when judging the OA tritone as rising or falling. In Experiments 2 and 3, participants compared the pitch heights of single OA and UA tones representing either the same pitch class or being a tritone apart. These judgments were strongly influenced by the pitch range of the UA tones, but only slightly by the spectral center of the OA tones. Thus, the perceived pitch height of single OA tones is context sensitive, but the perceived relative pitch height of two OA tones, as described in previous research on the “tritone paradox,” is largely invariant in UA tone contexts.     

The effect of Stroop interference on the categorical perception of color

In two experiments, we examined the effects of Stroop interference on the categorical perception (CP; better cross-category than within-category discrimination) of color. Using a successive two-alternative forced choice recognition paradigm (deciding which of two stimuli was identical to a previously presented target), which combined to-be-remembered colors with congruent and incongruent Stroop words, we found that congruent color words facilitated CP, whereas incongruent color words reduced CP. However, this was the case only when Stroop interference was presented together with the target color, but not when Stroop stimuli were introduced at the test stage. This suggests that target name, but not test name generation, affects CP. Target name generation may be important for CP because it acts as a category prime, which, in turn, facilitates cross-category discrimination.     

A unified account of categorical effects in phonetic perception

Categorical effects are found across speech sound categories, with the degree of these effects ranging from extremely strong categorical perception in consonants to nearly continuous perception in vowels. We show that both strong and weak categorical effects can be captured by a unified model. We treat speech perception as a statistical inference problem, assuming that listeners use their knowledge of categories as well as the acoustics of the signal to infer the intended productions of the speaker. Simulations show that the model provides close fits to empirical data, unifying past findings of categorical effects in consonants and vowels and capturing differences in the degree of categorical effects through a single parameter.     

Musical duplex perception: perception of figurally good chords with subliminal distinguishing tones.

In a variant of duplex perception with speech, phoneme perception is maintained when distinguishing components are presented below intensities required for separate detection, forming the basis for the claim that a phonetic module takes precedence over nonspeech processing. This finding is replicated with music chords (C major and minor) created by mixing a piano fifth with a sinusoidal distinguishing tone (E or E flat). Individual threshold intensities for detecting E or E flat in the context of the fixed piano tones are established. Chord discrimination thresholds defined by distinguishing tone intensity were determined. Experiment 2 verified masked detection thresholds and subliminal chord identification for experienced musicians. Accurate chord perception was maintained at distinguishing tone intensities nearly 20 dB below the threshold for separate detection. Speech and music findings are argued to demonstrate general perceptual principles.     

声调范畴感知和声调复杂度对音乐音高感知的跨领域影响

采用音高识别与区分任务, 以汉语母语者、越南语母语者和俄语母语者为研究对象, 考察了两个语言加工层面的因素, 即声调范畴感知模式以及不同语言声调系统的复杂度差异对跨领域音乐音高感知的影响。结果发现: (1)汉语和越南语两组声调语言母语者听辨结果符合范畴感知模式, 而俄语母语者是连续感知。在语言和音乐两种刺激条件下, 声调语言母语者在范畴边界宽度、范畴内区分率、范畴间区分率以及区分峰度等指标上不存在显著差异。(2)汉语和越南语两组声调语言母语者的音乐音高区分任务结果差异不显著。实验结果表明: 在行为层面, 母语声调范畴感知模式可以迁移到音乐音高感知中, 但复杂声调系统并不能促进跨领域的音乐音高精细感知。实验结果从语言对音乐音高加工影响的角度支持了“共享论”。     

Effects of speaking rate and lexical status on phonetic perception

Among the contextual factors known to play a role in segmental perception are the rate at which the speech was produced and the lexical status of the item, that is, whether it is a meaningful word of the language. In a series of experiments on the word-initial /b/-/p/ voicing distinction, we investigated the conditions under which these factors operate during speech processing. The results indicated that under instructions of speeded responding, listeners could, on some trials, ignore some later occurring contextual information within the word that specified rate and lexical status. Importantly, however, they could not ignore speaking rate entirely. Although they could base their decision on only the early portion of the word, when doing so they treated the word as if it were physically short--that is to say, as if there were no later occurring information specifying a slower rate. This suggests that listeners always take account of rate when identifying the voicing value of a consonant, but precisely which information within the word is used to specify rate can vary with task demands.     

个体攻击性对愤怒表情类别知觉的影响

探讨了个体攻击性对愤怒表情加工中反应偏向和敏感性的影响。使用愤怒、恐惧原型生成表情连续体作为实验材料, 采用类别知觉实验范式考察了高、低攻击个体识别和辨别愤怒-恐惧连续体的类别转折点和斜率。结果发现, 与低攻击个体相比, 高攻击个体识别愤怒-恐惧连续体类别界线处的曲线斜率更大; 高攻击个体具有类别界线向恐惧一端偏移的倾向, 但并没有达到统计显著。这表明, 高攻击个体不存在敌意归因偏向, 而是对愤怒和恐惧表情的转变具有更高的敏感性。     

The nature of learned categorical perception effects: a psychophysical approach

Categorical perception is often cited as a striking example of cognitive influences on perception. However, some evidence suggests the term is a misnomer, with effects based on cognitive not perceptual processing. Here, using a psychophysical approach, we provide evidence consistent with a learned categorical perception effect that is dependent on analysis within the visual processing stream. An improvement in participants' discrimination between grating patterns that they had learned to place in different categories was 'tuned' around the orientation of the patterns experienced during category learning. Thus, here, categorical perception may result from attentionally modulated perceptual learning about diagnostic category features, based upon orientation-selective stages of analysis. This argues strongly that category learning can alter our perception of the world.     

Modeling the categorical perception of speech sounds: A step toward biological plausibility

Our native language has a lifelong effect on how we perceive speech sounds. Behaviorally, this is manifested as categorical perception, but the neural mechanisms underlying this phenomenon are still unknown. Here, we constructed a computational model of categorical perception, following principles consistent with infant speech learning. A self-organizing network was exposed to a statistical distribution of speech input presented as neural activity patterns of the auditory periphery, resembling the way sound arrives to the human brain. In the resulting neural map, categorical perception emerges from most single neurons of the model being maximally activated by prototypical speech sounds, while the largest variability in activity is produced at category boundaries. Consequently, regions in the vicinity of prototypes become perceptually compressed, and regions at category boundaries become expanded. Thus, the present study offers a unifying framework for explaining the neural basis of the warping of perceptual space associated with categorical perception.     

Infants' perception of timbre: classification of complex tones by spectral structure

Infants 7 to 8.5 months of age were tested for their discrimination of timbre or sound quality differences in the context of variable exemplars. They were familiarized with a set of complex tones with specified spectral structure; members of the set varied in fundamental frequency, intensity, or duration. Infants were then tested for their detection of tones that contrasted in spectral structure but were similar in other respects. They successfully differentiated the two spectral structures in the context of these variations, indicating that they can classify tonal stimuli on the basis of timbre. When the stimuli were organized into arbitrary categories, infants were unable to differentiate these categories, indicating that their performance with nonarbitrary categories was not attributable to memorization of the familiarized set.