Thinking the voice: neural correlates of voice perception

The human voice is the carrier of speech, but also an "auditory face" that conveys important affective and identity information. Little is known about the neural bases of our abilities to perceive such paralinguistic information in voice. Results from recent neuroimaging studies suggest that the different types of vocal information could be processed in partially dissociated functional pathways, and support a neurocognitive model of voice perception largely similar to that proposed for face perception.     

Structure and function of auditory cortex: music and speech

We examine the evidence that speech and musical sounds exploit different acoustic cues: speech is highly dependent on rapidly changing broadband sounds, whereas tonal patterns tend to be slower, although small and precise changes in frequency are important. We argue that the auditory cortices in the two hemispheres are relatively specialized, such that temporal resolution is better in left auditory cortical areas and spectral resolution is better in right auditory cortical areas. We propose that cortical asymmetries might have developed as a general solution to the need to optimize processing of the acoustic environment in both temporal and frequency domains.     

The False Modesty of the Identity Theory of Truth

The identity theory of truth, according to which true thoughts are identical with facts, is very hard to formulate. It oscillates between substantive versions, which are implausible, and a merely truistic version, which is difficult to distinguish from deflationism about truth. This tension is present in the form of identity theory that one can attribute to McDowell from his views on perception, and in the conception defended by Hornsby under that name     

Conditional reasoning and the Wason selection task: Biconditional interpretation instead of reasoning bias

Two experiments were conducted to show that the IF … THEN … rules used in the different versions of Wason's (1966 Wason, P. C. 1966. “Reasoning”. In New horizons in psychology I, Edited by: Foss, B. M. Harmondsworth, , UK: Penguin.  [Google Scholar]) selection task are not psychologically—though they are logically—equivalent. Some of these rules are considered by the participants as strict logical conditionals, whereas others are interpreted as expressing a biconditional relationship. A deductive task was used jointly with the selection task to show that the original abstract rule is quite ambiguous in this respect, contrary to deontic rules: the typical “error” made by most people may indeed be explained by the fact that they consider the abstract rule as a biconditional. Thus, there is no proper error or bias in the selection task as it is still argued, but a differential interpretation of the rule. The need for taking into account a pragmatic component in the process of reasoning is illustrated by the experiments.     

Judgments of duration, figure-ground contrast, and size for words and nonwords

Does the word-superiority effect on letter discrimination result in a word-superiority effect on duration judgments? We examined this question in five experiments. In the first four experiments, we have demonstrated that (1) words shown for 32-80 msec were judged as presented longer than non-words shown for the same duration; (2) this word-superiority effect persists if the stimuli are shown for an objective duration of up to 250 msec; and (3) these effects can be extended to judgments of figure-ground contrast and letter size. These findings extend existing data on effects of processing fluency on perceptual judgments. In Experiment 5, we found that duration judgments were higher for words than for pronounceable nonwords, and duration judgments were higher for pronounceable non-words than for nonpronounceable nonwords. We discuss the implications of this finding for the discrepancy-attribution hypothesis.     

Stereotype threat undermines intellectual performance by triggering a disruptive mental load

Research on stereotype threat has repeatedly demonstrated that the intellectual performance of social groups is particularly sensitive to the situational context in which tests are usually administered. In the present experiment, an adaptation of the Raven Advanced Progressive Matrices Test was introduced as a measure of cognitive ability. Results showed that individuals targeted by a reputation of intellectual inferiority scored lower on the test than did other people. However, when the identical test was not presented as a measure of cognitive ability, the achievement gap between the target and the control group disappeared. Using heart rate variability indices to assess mental workload, our findings showed that the situational salience of a reputation of lower ability undermined intellectual performance by triggering a disruptive mental load. Our results indicate that group differences in cognitive ability scores can reflect different situational burdens and not necessarily actual differences in cognitive ability.     

A "voice inversion effect?"

Voice is the carrier of speech but is also an "auditory face" rich in information on the speaker's identity and affective state. Three experiments explored the possibility of a "voice inversion effect," by analogy to the classical "face inversion effect," which could support the hypothesis of a voice-specific module. Experiment 1 consisted of a gender identification task on two syllables pronounced by 90 speakers (boys, girls, men, and women). Experiment 2 consisted of a speaker discrimination task on pairs of syllables (8 men and 8 women). Experiment 3 consisted of an instrument discrimination task on pairs of melodies (8 string and 8 wind instruments). In all three experiments, stimuli were presented in 4 conditions: (1) no inversion; (2) temporal inversion (e.g., backwards speech); (3) frequency inversion centered around 4000 Hz; and (4) around 2500 Hz. Results indicated a significant decrease in performance caused by sound inversion, with a much stronger effect for frequency than for temporal inversion. Interestingly, although frequency inversion markedly affected timbre for both voices and instruments, subjects' performance was still above chance. However, performance at instrument discrimination was much higher than for voices, preventing comparison of inversion effects for voices vs. non-vocal stimuli. Additional experiments will be necessary to conclude on the existence of a possible "voice inversion effect."     

Impossible shadows and the shadow correspondence problem

Shadows cast by objects contain potentially useful information about the location of these objects in the scene as well as their surface reflectance. However, before the visual system can use this information, it has to solve the shadow correspondence problem, that is to match the objects with their respective shadows. In the first experiment, it is shown that the estimate of the light source position is affected by a gradual luminance ramp added to the image. In the second experiment, it is shown that observers process impossible shadow images as if they ignored the local features of the objects. All together, the results suggest that the visual system solves the shadow correspondence problem by relying on a coarse representation of the scene.     

A first step toward cognitive remediation of voices: a case study

Several studies have shown that source-monitoring errors are related to verbal hallucinations in schizophrenia. An exploratory pilot study has been carried out to investigate the possibility of training patients in how to avoid errors in source-monitoring. One patient with paranoid schizophrenia and persistent thought insertions was trained for 6 hours to use mnemonic techniques to compensate specific deficits in source-monitoring. Results show that the patient was able to improve his performance and maintain the acquired progress at a 1-month follow-up assessment. These preliminary results are interesting for developing a larger controlled study of cognitive remediation of source-monitoring deficits.