Perceptual scaling of voice identity: common dimensions for different vowels and speakers

The aims of our study were: (1) to determine if the acoustical parameters used by normal subjects to discriminate between different speakers vary when comparisons are made between pairs of two of the same or different vowels, and if they are different for male and female voices; (2) to ask whether individual voices can reasonably be represented as points in a low-dimensional perceptual space such that similarly sounding voices are located close to one another. Subjects were presented with pairs of voices from 16 male and 16 female speakers uttering the three French vowels “a”, “i” and “u” and asked to give speaker similarity judgments. Multidimensional analyses of the similarity matrices were performed separately for male and female voices and for three types of comparisons: same vowels, different vowels and overall average. The resulting dimensions were then interpreted a posteriori in terms of relevant acoustical measures. For both male and female voices, a two-dimensional perceptual space was found to be most appropriate, with axes largely corresponding to contributions of the larynx (pitch) and supra-laryngeal vocal tract (formants), mirroring the two largely independent components of source and filter in voice production. These perceptual spaces of male and female voices and their corresponding voice samples are available at: section Resources.     

A new look at sensory attenuation. Action-effect anticipation affects sensitivity, not response bias

The systematic association of an action that a person performs with its sensory effects is thought to attenuate that person's perception of the effect of the action. However, whether learned sensorimotor contingencies truly affect perception, rather than just inducing a response bias, has yet to be determined. The experiment presented in this article comprised two parts: an action-effect association phase and a test phase, during which the actions' perceptual effects were tested. During the association phase, specific actions (left-key and right-key presses) were associated with specific visual effects (tilted Gabor patches). In the test phase, participants' left-key presses and right-key presses triggered the onset of a low-contrast tilted Gabor patch in 50% of trials (no stimulus was presented on the remaining 50% of trials). Participants were required to report the presence or absence of this tilted Gabor patch. Our results showed that participants' sensitivity (d') to the Gabor patches was reduced by 10% when the patches were triggered by the action they had previously been associated with. This finding indicates that a person's action does not induce a response bias (c), but changes the perception (d') of the learned action effect.     

Keeping the vermin out: Perceived disease threat and ideological orientations as predictors of exclusionary immigration attitudes

Integrating evolutionary and social representations theories, the current study examines the relationship between perceived disease threat and exclusionary immigration attitudes in the context of a potential avian influenza pandemic. This large‐scale disease provides a realistic context for investigating the link between disease threat and immigration attitudes. The main aim of this cross‐sectional study (N = 412) was to explore mechanisms through which perceived chronic and contextual disease threats operate on immigration attitudes. Structural equation models show that the relationship between chronic disease threat (germ aversion) and exclusionary immigration attitudes (assimilationist immigration criteria, health‐based immigration criteria and desire to reduce the proportion of foreigners) was mediated by ideological and normative beliefs (social dominance orientation, belief in a dangerous world), but not by contextual disease threat (appraisal of avian influenza pandemic threat). Contextual disease threat only predicted support for health‐based immigration criteria. The conditions under which real‐life disease threats influence intergroup attitudes are scrutinized. Convergence and dissimilarity of evolutionary and social representational approaches in accounting for the link between disease threat and immigration attitudes are discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Exploring the temporal dynamics of social facilitation in the Stroop task

The importance of social context in affecting attention has recently been highlighted by the finding that the presence of a passive, nonevaluative confederate can improve selective attention. The underlying mechanism, however, remains unclear. In this paper, we argue that social facilitation can be caused by distractor inhibition. Two distinct sources of evidence are provided from an experiment employing the Stroop task with and without social presence. First, analysis of the response time (RT) distribution indicates that interference is reduced at relatively long RTs. This is consistent with an inhibitory mechanism, whose effects build up slowly. Further support is provided by showing that social facilitation is prevented by using short response-to-stimulus intervals that are thought to reduce cognitive control processes.     

Cross-modal facilitation in speech prosody

Speech prosody has traditionally been considered solely in terms of its auditory features, yet correlated visual features exist, such as head and eyebrow movements. This study investigated the extent to which visual prosodic features are able to affect the perception of the auditory features. Participants were presented with videos of a speaker pronouncing two words, with visual features of emphasis on one of these words. For each trial, participants saw one video where the two words were identical in both pitch and amplitude, and another video where there was a difference in either pitch or amplitude that was congruent or incongruent with the visual changes. Participants were asked to decide which video contained the sound difference. Thresholds were obtained for the congruent and incongruent videos, and for an auditory-alone condition. It was found that the congruent thresholds were better than the incongruent thresholds for both pitch and amplitude changes. Interestingly, the congruent thresholds for amplitude were better than for the auditory-alone condition, which implies that the visual features improve sensitivity to loudness changes. These results demonstrate that visual stimuli can affect auditory thresholds for changes in pitch and amplitude, and furthermore support the view that visual prosodic features enhance speech processing.     

Power increases the self-serving bias in the attribution of collective successes and failures

Three studies test the effect of power on the self-serving bias in attributing collective outcomes. The first two studies measure (Experiment 1) and manipulate (Experiment 2) power and then measure the internal (vs. external) attribution of past successes and failures. Consistently, those who feel powerful show a stronger self-serving tendency to selectively attribute successes internally and failures externally than those who feel powerless. Experiment 3 compares the effects of power (control over others) and personal control (over oneself). We find that power increases the self-serving bias, but a lack of control can limit this effect by reducing the external attribution of failures. Presumably, people who lack control are disinclined to attribute outcomes—including failures—externally because doing so would further aggravate their lack of control. Together, these results suggest that power increases a bias in the attribution of success and failure and thus presents a fundamental challenge to good leadership.     

Towards global integration

The struggle against exclusion must be a global struggle, for it must take into account everything that makes up the life of every individual. Businesses have a central role, for they can offer training to those young people who see school only as a failure.     

The counterintuitive impact of responses and response times on parameter estimates in the drift diffusion model

Given a drift diffusion model with unknown drift and boundary parameters, we analyse the behaviour of maximum likelihood estimates with respect to changes of responses and response times. It is shown analytically that a single fast response time can dominate the estimation in that no matter how many correct answers a test taker provides, the estimate of the drift (ability) parameter decreases to zero. In addition, it is shown that although higher drift rates imply shorter response times, the reverse implication does not hold for the estimates: shorter response times can decrease the drift rate estimate. In the light of these analytical results, we illustrate the actual impact of the findings in a small simulation for a mental rotation test. The method of analysis outlined is applicable to a broader range of models, and we emphasize the need to further check currently used reaction time models within this framework.