Perceptual expertise and the plasticity of other-race face recognition

In this paper, we argue that our ability to recognize own-race faces can be treated as a form of perceptual expertise. Similar to object experts (e.g., birdwatchers), people differentiate own-race faces at the subordinate level of categorization. In contrast, like novices, we tend to classify other-race faces at the basic level of race. We demonstrate that, as a form of perceptual expertise, other-race face recognition can be systematically taught in the lab through subordinate-level training. When participants learn to quickly and accurately differentiate other-race faces at the subordinate level of the individual, the individuating training transfers to improved recognition of untrained other-race faces, produces changes in event-related brain components, and reduces implicit racial bias. Subsequent work has shown that other-race learning can be optimized by directing participants to the diagnostic features of a racial group. The benefits of other-race training are fairly long-lived and are evident even 2 weeks after training. Collectively, the training studies demonstrate the plasticity of other-race face recognition. Rather than a process that is fixed by early developmental events, other-race face recognition is malleable and dynamic, continually being reshaped by the perceptual experiences of the observer.     

Electrophysiological evidence for colour effects on the naming of colour diagnostic and noncolour diagnostic objects

In this study, we investigated the level of visual processing at which surface colour information improves the naming of colour diagnostic and noncolour diagnostic objects. Continuous electroencephalograms were recorded while participants performed a visual object naming task in which coloured and black-and-white versions of both types of objects were presented. The black-and-white and the colour presentations were compared in two groups of event-related potentials (ERPs): (1) The P1 and N1 components, indexing early visual processing; and (2) the N300 and N400 components, which index late visual processing. A colour effect was observed in the P1 and N1 components, for both colour and noncolour diagnostic objects. In addition, for colour diagnostic objects, a colour effect was observed in the N400 component. These results suggest that colour information is important for the naming of colour and noncolour diagnostic objects at different levels of visual processing. It thus appears that the visual system uses colour information, during naming of both object types, at early visual stages; however, for the colour diagnostic objects naming, colour information is also recruited during the late visual processing stages.     

The role of rigid motion in newborns' face recognition

The study investigated whether dynamic information promotes newborns' ability to recognize a face. After being habituated to a face undergoing an ordered sequential head rigid motion (Exp. 1), 1- to 3-day-old newborns fully recognized the familiar face shown in the profile pose, as documented by a preference for the profile pose of a novel face. When familiarized to an ordered sequence of different viewpoint static images of a face (Exp. 2), newborns failed to recognize the profile pose of the familiar face, their visual exploration of the familiar and novel faces being at chance. Habituation to a random head rigid motion (Exp. 3) allowed only a partial recognition of face identity, as newborns preferred the profile pose of the familiar, rather than the novel, face. Rigid head motion is an important source of information for newborns' face recognition, probably aiding the derivation of a three-dimensional face structure.     

Basal ganglia, dopamine and temporal processing: performance on three timing tasks on and off medication in Parkinson's disease

A pervasive hypothesis in the timing literature is that temporal processing in the milliseconds and seconds range engages the basal ganglia and is modulated by dopamine. This hypothesis was investigated by testing 12 patients with Parkinson's disease (PD), both 'on' and 'off' dopaminergic medication, and 20 healthy controls on three timing tasks. In a seconds range (30-120 s) time production task, patients tested 'on' medication showed a significantly different accuracy profile compared to controls and when tested 'off' medication. However, no group or on vs off medication differences in accuracy were found on a time reproduction task and a warned reaction time task requiring temporal processing within the 250-2000 ms range. Variability was measured using the coefficient of variation, with the performance of the patient group on the time reproduction task violating the scalar property, suggesting atypical temporal processing mechanisms. The data suggest that the integrity of the basal ganglia is necessary for 'typical' time production in the seconds range as well as for time reproduction at shorter intervals. Exploratory factor analysis suggested that the time production task uses neural mechanisms distinct from those used in the other two timing tasks. The dissociation of the effects of dopaminergic medication and nature of task on performance in PD raises interesting questions about the pharmacological mediation and task-specificity of deficits in temporal processing.     

Discrepant fluency increases subjective truth

The present experiment tested the hypothesis that perceptual fluency affects truth judgments especially when the fluency has changed. Participants were asked to judge the truth of statements that were printed in different colors. Perceptual fluency was manipulated by color contrast. Change versus no change of fluency was manipulated by using preceding statements that had the same or a different contrast. As expected, highly fluent statements were judged as more probably true than statements with a low fluency but this effect occurred only when the high fluency meant a change from previous fluency. The role of discrepancies in subjective experiences in terms of their informativeness for social judgments is discussed.     

Dissimilarity cumulation theory in smoothly connected spaces

This is the third paper in the series introducing the Dissimilarity Cumulation theory and its main psychological application, Universal Fechnerian Scaling. The previously developed dissimilarity-based theory of path length is used to construct the notion of a smooth path, defined by the property that the ratio of the dissimilarity between its points to the length of the subtended fragment of the path tends to unity as the points get closer to each other. We consider a class of stimulus spaces in which for every path there is a series of piecewise smooth paths converging to it pointwise and in length; and a subclass of such spaces where any two sufficiently close points can be connected by a smooth “geodesic in the small”. These notions are used to construct a broadly understood Finslerian geometry of stimulus spaces representable by regions of Euclidean n-spaces. With an additional assumption of comeasurability in the small between the canonical psychometric increments of the first and second kind, this establishes a link between Universal Fechnerian Scaling and Multidimensional Fechnerian Scaling in Euclidean n-spaces. The latter was a starting point for our theoretical program generalizing Fechner’s idea that sensation magnitudes can be computed by integration of a local discriminability measure.     

On minima of discrimination functions

A discrimination function ψ(x,y) assigns a measure of discriminability to stimulus pairs x,y (e.g., the probability with which they are judged to be different in a same-different judgment scheme). If for every x there is a single y least discriminable from x, then this y is called the point of subjective equality (PSE) for x, and the dependence h(x) of the PSE for x on x is called a PSE function. The PSE function g(y) is defined in a symmetrically opposite way. If the graphs of the two PSE functions coincide (i.e., g≡h⁻¹), the function is said to satisfy the Regular Minimality law. The minimum level functions are restrictions of ψ to the graphs of the PSE functions. The conjunction of two characteristics of ψ, (1) whether it complies with Regular Minimality, and (2) whether the minimum level functions are constant, has consequences for possible models of perceptual discrimination. By a series of simple theorems and counterexamples, we establish set-theoretic, topological, and analytic properties of ψ which allow one to relate to each other these two characteristics of ψ.     

The weckud wetch of the wast: lexical adaptation to a novel accent

Two experiments investigated the mechanism by which listeners adjust their interpretation of accented speech that is similar to a regional dialect of American English. Only a subset of the vowels of English (the front vowels) were shifted during adaptation, which consisted of listening to a 20-min segment of the "Wizard of Oz." Compared to a baseline (unadapted) condition, listeners showed significant adaptation to the accented speech, as indexed by increased word judgments on a lexical decision task. Adaptation also generalized to test words that had not been presented in the accented passage but that contained the shifted vowels. A control experiment showed that the adaptation effect was specific to the direction of the shift in the vowel space and not to a general relaxation of the criterion for what constitutes a good exemplar of the accented vowel category. Taken together, these results provide evidence for a context-specific vowel adaptation mechanism that enables a listener to adjust to the dialect of a particular talker.     

Context Effects on Musical Chord Categorization: Different Forms of Top‐Down Feedback in Speech and Music?

A critical issue in perception is the manner in which top-down expectancies guide lower level perceptual processes. In speech, a common paradigm is to construct continua ranging between two phonetic endpoints and to determine how higher level lexical context influences the perceived boundary. We applied this approach to music, presenting participants with major/minor triad continua after brief musical contexts. Two experiments yielded results that differed from classic results in speech perception. In speech, context generally expands the category of the expected stimuli. We found the opposite in music: The major/minor boundary shifted toward the expected category, contracting it. Together, these experiments support the hypothesis that musical expectancy can feed back to affect lower-level perceptual processes. However, it may do so in a way that differs fundamentally from what has been seen in other domains.     

不同掩蔽材料对阅读知觉广度的影响

采用移动窗口技术,探讨了不同掩蔽材料对中文阅读知觉广度的影响,结果表明：（1）相对于“※”掩蔽,文字掩蔽条件下的阅读效率更低、平均注视时间更长、眼跳幅度更小。（2）“※”掩蔽下被试的知觉广度为注视字左侧1个字,右侧2－3个字;文字掩蔽下被试的知觉广度为注视字左侧1个字,右侧3－4个字。综合上述结果,文字掩蔽材料可以比“※”掩蔽材料获得更大的知觉广度,但阅读效率更低。在中文阅读中,文字掩蔽材料更适合探讨阅读知觉广度