Speech perception as categorization

Speech perception (SP) most commonly refers to the perceptual mapping from the highly variable acoustic speech signal to a linguistic representation, whether it be phonemes, diphones, syllables, or words. This is an example of categorization, in that potentially discriminable speech sounds are assigned to functionally equivalent classes. In this tutorial, we present some of the main challenges to our understanding of the categorization of speech sounds and the conceptualization of SP that has resulted from these challenges. We focus here on issues and experiments that define open research questions relevant to phoneme categorization, arguing that SP is best understood as perceptual categorization, a position that places SP in direct contact with research from other areas of perception and cognition.     

Stepping up the pressure: arousal can be associated with a reduction in male aggression

The attentional myopia model of behavioral control [Mann and Ward, 2007] was tested in an experiment investigating the relationship between physiological arousal and aggression. Drawing on previous work linking arousal and narrowed attentional focus, the model predicts that arousal will lead to behavior that is relatively disinhibited in situations in which promoting pressures to aggress are highly salient. In situations in which inhibitory pressures are more salient, the model predicts behavior that is relatively restrained. In the experiment, 81 male undergraduates delivered noise-blasts against a provoking confederate while experiencing either high or low levels of physiological arousal and, at the same time, being exposed to cues that served either to promote or inhibit aggression. In addition to supporting the predictions of the model, this experiment provided some of the first evidence for enhanced control of aggression under conditions of heightened physiological arousal. Implications for interventions designed to reduce aggression are discussed.     

Stress management interventions for HIV+ adults: a meta-analysis of randomized controlled trials, 1989 to 2006.

OBJECTIVE: Numerous studies document that stress accelerates disease processes in a variety of diseases including HIV. As a result, investigators have developed and evaluated interventions to reduce stress as a means to improve health among persons living with HIV. Therefore, the current meta-analysis examines the impact of stress-management interventions at improving psychological, immunological, hormonal, and other behavioral health outcomes among HIV+ adults. DESIGN: This meta-analytic review integrated the results of 35 randomized controlled trials examining the efficacy of 46 separate stress management interventions for HIV+ adults (N=3,077). MAIN OUTCOME MEASURES: Effect sizes were calculated for stress processes (coping and social support), psychological/psychosocial (anxiety, depression, distress, and quality of life), immunological (CD4+ counts and viral load), hormonal (cortisol, dehydroepiandrosterone sulfate [DHEA-S], cortisol/DHEA-S ratio, and testosterone) and other behavioral health outcomes (fatigue). RESULTS: Compared to controls, stress-management interventions reduce anxiety, depression, distress, and fatigue and improve quality of life (d+s=0.16 to 0.38). Stress-management interventions do not appear to improve CD4+ counts, viral load, or hormonal outcomes compared with controls. CONCLUSION: Overall, stress-management interventions for HIV+ adults significantly improve mental health and quality of life but do not alter immunological or hormonal processes. The absence of immunological or hormonal benefits may reflect the studies' limited assessment period (measured typically within 1-week postintervention), participants' advanced stage of HIV (HIV+ status known for an average of 5 years), and/or sample characteristics (predominately male and White participants). Future research might test these hypotheses and refine our understanding of stress processes and their amelioration.     

Cognitive responses to failure and success relate uniquely to bipolar depression versus mania

This project examined cognitive responses to failure and success and their association with depression and mania within bipolar disorder. Many cognitive variables that are associated with unipolar depression have been found to be involved in bipolar disorder, more specifically bipolar depression. This research was the first to examine tendencies to hold high standards, engage in self-criticism, and generalize from failure to an overall sense of self-worth. In Study 1, undergraduates were screened for risk of mood disorders and completed structured diagnostic interviews. History of bipolar spectrum disorders and history of depression had separate associations with negative generalization. The association of generalization with bipolar spectrum disorders was accounted for by current depressive symptoms. For Study 2, the authors developed a measure of the tendency to engage in positive generalization following success experiences. In a sample of 276 undergraduates, this measure related uniquely to risk for mania. Results of these 2 studies suggest that responses to failure are associated with a history of depression, whereas responses to success are associated with a risk for mania. Implications for future research and clinical work are discussed.     

Managers’ and Subordinates’ Evaluations of Feedback Strategies: The Critical Contribution of Voice1

This study investigated 87 managers’ and 91 subordinates’ evaluations of a range of strategies for delivering performance feedback in the workplace. The managers and subordinates rated 8 written vignettes describing different feedback strategies on a number of variables (perceived effectiveness, perceived risk, level of enactment demand, and congruence of strategy for managers). Feedback strategies that used an invitation for the subordinate to reply to the negative feedback were evaluated as more effective and managerially congruent, and less risky than were the other strategies. However, strategies requiring bidirectional communication (e.g., invitations to reply), as opposed to unidirectional communication (e.g., praise), were generally perceived as more demanding to enact.     

Effects of Attention on the Strength of Lexical Influences on Speech Perception: Behavioral Experiments and Computational Mechanisms

The effects of lexical context on phonological processing are pervasive and there have been indications that such effects may be modulated by attention. However, attentional modulation in speech processing is neither well documented nor well understood. Experiment 1 demonstrated attentional modulation of lexical facilitation of speech sound recognition when task and critical stimuli were identical across attention conditions. We propose modulation of lexical activation as a neurophysiologically plausible computational mechanism that can account for this type of modulation. Contrary to the claims of critics, this mechanism can account for attentional modulation without violating the principle of interactive processing. Simulations of the interactive TRACE model extended to include two different ways of modulating lexical activation showed that each can account for attentional modulation of lexical feedback effects. Experiment 2 tested conflicting predictions from the two implementations and provided evidence that is consistent with bias input as the mechanism of attentional control of lexical activation.     

Workload Variability and Social Support: Effects on Stress and Performance

The current study investigated the effect of workload variability on performance and stress, as well as the role of social support as a potential intervention. Based on previous research it was predicted that a shift in workload from either high to low or low to high would lower performance and increase stress, while the provision of social support would result in higher performance and lower stress. Results revealed significant decrements in performance following workload shifts, though no increase in stress was perceived. Performance in both workload conditions significantly, but inconsistently, increased following the provision of social support and stress significantly decreased following the shift from high to low workload. Implications and future research steps are discussed further.     

Workload Variability and Social Support: Effects on Stress and Performance

The current study investigated the effect of workload variability on performance and stress, as well as the role of social support as a potential intervention. Based on previous research it was predicted that a shift in workload from either high to low or low to high would lower performance and increase stress, while the provision of social support would result in higher performance and lower stress. Results revealed significant decrements in performance following workload shifts, though no increase in stress was perceived. Performance in both workload conditions significantly, but inconsistently, increased following the provision of social support and stress significantly decreased following the shift from high to low workload. Implications and future research steps are discussed further.     

Temporally selective attention modulates early perceptual processing: event-related potential evidence

Some of the most important information we encounter changes so rapidly that our perceptual systems cannot process all of it in detail. Spatially selective attention is critical for perception when more information than can be processed in detail is presented simultaneously at distinct locations. When presented with complex, rapidly changing information, listeners may need to selectively attend to specific times rather than to locations. We present evidence that listeners can direct selective attention to time points that differ by as little as 500 msec, and that doing so improves target detection, affects baseline neural activity preceding stimulus presentation, and modulates auditory evoked potentials at a perceptually early stage. These data demonstrate that attentional modulation of early perceptual processing is temporally precise and that listeners can flexibly allocate temporally selective attention over short intervals, making it a viable mechanism for preferentially processing the most relevant segments in rapidly changing streams.