The role of visual information in the processing of

Visual information provided by a talker’s mouth movements can influence the perception of certain speech features. Thus, the “McGurk effect” shows that when the syllable /bi/ is presented audibly, in synchrony with the syllable /gi/, as it is presented visually, a person perceives the talker as saying /di/. Moreover, studies have shown that interactions occur between place and voicing features in phonetic perception, when information is presented audibly. In our first experiment, we asked whether feature interactions occur when place information is specified by a combination of auditory and visual information. Members of an auditory continuum ranging from /ibi/ to /ipi/ were paired with a video display of a talker saying /igi/. The auditory tokens were heard as ranging from /ibi/ to /ipi/, but the auditory-visual tokens were perceived as ranging from /idi/ to /iti/. The results demonstrated that the voicing boundary for the auditory-visual tokens was located at a significantly longer VOT value than the voicing boundary for the auditory continuum presented without the visual information. These results demonstrate that place-voice interactions are not limited to situations in which place information is specified audibly. In three follow-up experiments, we show that (1) the voicing boundary is not shifted in the absence of a change in the global percept, even when discrepant auditory-visual information is presented; (2) the number of response alternatives provided for the subjects does not affect the categorization or the VOT boundary of the auditory-visual stimuli; and (3) the original effect of a VOT boundary shift is not replicated when subjects are forced by instruction to \ldrelabel\rd the /b-p/auditory stimuli as/d/or/t/. The subjects successfully relabeled the stimuli, but no shift in the VOT boundary was observed.     

Altering information to gain action control: Functional aspects of human information processing in decision making

In recent approaches to social judgment, information distortion has been discussed primarily as a violation of individual rationality, due to unintentionally occurring biases. In contrast to this view, it is argued that frequently individuals make purposive use of selective changes in information processing in order to avoid indecisiveness. In this sense, selective changes in information processing may be considered a functional requirement of a volitional process which protects the current intention (or tentative decision) from being replaced by competing behavioral tendencies. On the basis of J. Kuhl's theory of action control (1981, Journal of Personality and Social Psychology, 40, 155–170; 1982, in W. Hacker, W. Volpert, & M. von Cranach, Eds., Cognitive and Motivational Aspects of Action, Amsterdam: North-Holland, 1984, in B. A. Maher, Progress in Experimental Personality Research, Vol. 13, New York: Academic Press) it was predicted that subjects having a high score on the action-control scale (i.e., action-oriented subjects) should show a stronger tendency to increase the attractiveness rating of a tentatively preferred decision during the process of decision making than subjects scoring low on that scale (i.e., state-oriented subjects). To test this assumption, students searching for an apartment were offered 16 apartments along with a list containing information about the alternatives. The subjects had to rate the attractiveness of each apartment twice before they were asked to indicate which apartments they would like to rent. The results confirmed the predictions. It was found that action-oriented subjects increased the divergence of their attractiveness ratings from the first to the second point of evaluation, whereas state-oriented subjects did not.     

Cerebral Anesthetization for Localization of Speech: The Contribution of W. James Gardner

In 1949, the neurologist Juhn Wada reported the first use of a new procedure for determining the localization of speech and language in neurological patients: examination of the effects on speech and language after injecting a barbiturate, sodium amytal, into the internal carotid artery of each hemisphere in succession. By the 1960s, Wada'sIntracarotid Amobarbital Procedure,orIAP,had become the method of choice for identifying the speech-dominant side in one kind of neurological patient, persons with epilepsy who are candidates for surgical resection, and it remains so today. In 1941, however, an American neurosurgeon, W. James Gardner, reported his use of a different anesthetization procedure for speech localization in neurological patients. Instead of injecting sodium amytal through the blood supply, as in the IAP, Gardner injected procaine hydrochloride directly into cortical tissue. In this paper, we provide a brief biography of Gardner. We then discuss his method of cortical anesthetization, the theoretical and empirical background guiding his use of this method and his choice of patients, and, finally, the fate of Gardner's method within the scientific community.     

Game Theory and Rational Decision

In its classical conception, game theory aspires to be a determinate decision theory for games, understood as elements of a structurally specified domain. Its aim is to determine for each game in the domain a complete solution to each player's decision problem, a solution valid for all real-world instantiations, regardless of context. “Permissiveness” would constrain the theory to designate as admissible for a player any conjecture consistent with the function's designation of admissible strategies for the other players. Given permissiveness and other appropriate constraints, solution sets must contain only Nash equilibria and at least one pure-strategy equilibrium, and there is no solution to games in which no symmetry invariant set of pure-strategy equilibria forms a Cartesian product. These results imply that the classical program is unrealizable. Moreover, the program is implicitly committed to permissiveness, through its common-knowledge assumptions and its commitment to equilibrium. The resulting incoherence deeply undermines the classical conception in a way that consolidates a long series of contextualist criticisms. This revised version was published online in July 2006 with corrections to the Cover Date.     

Integral processing of visual place and auditory voicing information during phonetic perception.

Results of auditory speech experiments show that reaction times (RTs) for place classification in a test condition in which stimuli vary along the dimensions of both place and voicing are longer than RTs in a control condition in which stimuli vary only in place. Similar results are obtained when subjects are asked to classify the stimuli along the voicing dimension. By taking advantage of the "McGurk" effect (McGurk & MacDonald, 1976), the present study investigated whether a similar pattern of interference extends to situations in which variation along the place dimension occurs in the visual modality. The results showed that RTs for classifying phonetic features in the test condition were significantly longer than in the control condition for the place and voicing dimensions. These results indicate a mutual and symmetric interference exists in the classification of the two dimensions, even when the variation along the dimensions occurs in separate modalities.     

Human adults and human infants show a “perceptual magnet effect” for the prototypes of speech categories,monkeys do not

Many perceptual categories exhibit internal structure in which category prototypes play an important role. In the four experiments reported here, the internal structure of phonetic categories was explored in studies involving adults, infants, and monkeys. In Experiment 1, adults rated the category goodness of 64 variants of the vowel /i/ on a scale from 1 to 7. The results showed that there was a certain location in vowel space where listeners rated the /i/ vowels as best instances, or prototypes. The perceived goodness of Iii vowels declined systematically as stimuli were further removed from the prototypic Iii vowel. Experiment 2 went beyond this initial demonstration and examined the effect of speech prototypes on perception. Either the prototypic or a nonprototypic IM vowel was used as the referent stimulus and adults’ generalization to other members of the category was examined. Results showed that the typicality of the speech stimulus strongly affected perception. When the prototype of the category served as the referent vowel, there was significantly greater generalization to other /i/ vowels, relative to the situation in which the nonprototype served as the referent. The notion of aperceptual magnet was introduced. The prototype of the category functioned like a perceptual magnet for other category members; it assimilated neighboring stimuli, effectively pulling them toward the prototype. In Experiment 3, the ontogenetic origins of the perceptual magnet effect were explored by testing 6-month-old infants. The results showed that infants’ perception of vowels was also strongly affected by speech prototypes. Infants showed significantly greater generalization when the prototype of the vowel category served as the referent; moreover, their responses were highly correlated with those of adults. In Experiment 4, Rhesus monkeys were tested to examine whether or not the prototype’s magnet effect was unique to humans. The animals did not provide any evidence of speech prototypes; they did not exhibit the magnet effect. It is suggested that the internal organization of phonetic categories around prototypic members is an ontogenetically early, species-specific, aspect of the speech code     

Das biologische Individuum

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