Dichotic listening and sleep deprivation: vigilance effects

Twelve sleep-deprived and 13 non-deprived Navy cadets were tested with the dichotic listening procedure for effects of sleep deprivation on hemispheric asymmetry and sustained attention. Consonant-vowel syllables were presented to the subjects in three different conditions, a divided (non-forced) attention condition, a forced right ear and a forced left ear attention condition. In the two forced attention conditions the subjects were instructed to focus attention only on the right or left ear stimulus. The results showed an expected right ear advantage for both groups during the non-forced and forced right attention conditions, indicating superior left hemisphere processing. During the forced left attention condition, the sleep-deprived subjects showed no ear advantage at all, while the non-deprived subjects showed an expected left ear advantage. The results are discussed within a theoretical framework of a dual process model, where sleep deprivation disrupts the ability to sustain attention, caused by a temporary failure of the right hemisphere's top-down (instruction-driven) processing to override the left hemisphere's bottom-up (stimulus-driven) processing.     

Temporal parameters as cues to phrasal boundaries: a comparison of processing by left- and right-hemisphere brain-damaged individuals

Two experiments were conducted to examine the ability of left- (LHD) and right-hemisphere-damaged (RHD) patients and normal controls to use temporal cues in rendering phrase grouping decisions. The phrase "pink and black and green" was manipulated to signal a boundary after "pink" or after "black" by altering pre-boundary word durations and pause durations at the boundary in a stepwise fashion. Stimuli were presented to listeners auditorily along with a card with three alternative groupings of colored squares from which to select the presented alternative. Results revealed that normal controls were able to use both temporal cues to identify the intended grouping. In contrast, LHD patients required longer than normal pause durations to consistently identify the intended grouping, suggesting a higher than normal threshold for perception of temporal prosodic cues. Surprisingly, the RHD patients exhibited great difficulty with the task, perhaps due to the limited acoustic cues available in the stimuli.     

Contribution of acetylcholine to visual cortex plasticity

Acetylcholine is involved in a variety of brain functions. In the visual cortex, the pattern of cholinergic innervation varies considerably across different mammalian species and across different cortical layers within the same species. The physiological effects of acetylcholine in the visual cortex display complex responses, which are likely due to cholinergic receptor subtype composition in cytoplasm membrane as well as interaction with other transmitter systems within the local neural circuitry. The functional role of acetylcholine in visual cortex is believed to improve the signal-to-noise ratio of cortical neurons during visual information processing. Available evidence suggests that acetylcholine is also involved in experience-dependent visual cortex plasticity. At the level of synaptic transmission, activation of muscarinic receptors has been shown to play a permissive role in visual cortex plasticity. Among the muscarinic receptor subtypes, the M(1) receptor seems to make a predominant contribution towards modifications of neural circuitry. The signal transduction cascade of the cholinergic pathway may act synergistically with that of the NMDA receptor pathway, whose activation is a prerequisite for cortical plasticity.     

Interhemispheric effects of simulated lesions in a neural model of single-word reading

A neural model consisting of paired cerebral hemispheric regions interacting via homotopic callosal connections was trained to generate pronunciations for 50 monosyllabic words. Lateralization of this task occurred readily when different underlying cortical asymmetries were present. Following simulated focal cortical lesions of systematically varied sizes, acute changes in the distribution of cortical activation were found to be most consistent with experimental data when interhemispheric interactions were assumed to be excitatory. During subsequent recovery, the contribution of the unlesioned hemispheric region to performance improvement was a function of both the amount of preexisting lateralization and the side and size of the lesion. These results are discussed in the context of unresolved issues concerning the mechanisms underlying language lateralization, the nature of interhemispheric interactions, and the role of the nondominant hemisphere in recovery from adult aphasia.     

Veg*ns’ and omnivores’ reciprocal attitudes and dehumanization: The role of social dominance orientation,ingroup identification,and anticipated reproach

Two studies compared omnivores’ and veg*ns’ attitudes and dehumanization tendencies toward each other and identified the social psychological factors explaining them. Study 1 (N = 208, Italians) showed that veg*ns’ hold less positive attitudes toward omnivores than the reverse, and attributed to them less human uniqueness and nature; these differences were explained by veg*ns’ stronger identification with the ingroup and higher perceptions of reproach from the outgroup, even if omnivores’ higher levels of social dominance orientation worsened their attitude toward veg*ns. Study 2 (preregistered, N = 200, mostly from UK) overall replicated Study 1 findings at the explicit level. Interestingly, omnivores’ and veg*ns’ implicit attitudes were equally positive (but less positive than self-reported attitudes) and not predicted by the same mediators associated with the explicit measures. This work suggests that neither veg*ns nor omnivores hold negative attitudes toward each other: they were both positive or neutral toward the outgroup, even if at the explicit level this positivity is greater for omnivores.     

The influence of vestibular system and fetal presentation on handedness,cognitive and motor development: A comparison between cephalic and breech presentation

Genetics are undoubtedly implicated in the ontogenesis of laterality. Nonetheless, environmental factors, such as the intrauterine environment, may also play a role in the development of functional and behavioral lateralization. The aim of this study was to test the Left-Otolithic Dominance Theory (LODT; Previc, 1991) by investigating a hypothetical developmental pattern where it is assumed that a breech presentation, which is putatively associated with a dysfunctional and weakly lateralized vestibular system, can lead to weak handedness and atypical development associated with language and motor difficulties. We used the ALSPAC cohort of children from 7 to 10 years of age to conduct our investigation. Our results failed to show an association between the vestibular system and fetal presentation, nor any influence of the latter on hand preference, hand performance, or language and motor development. Bayesian statistical analyses supported these findings. Contrary to our LODT-derived hypotheses, this study offers evidence that fetal presentation does not influence the vestibular system's lateralization and seems to be a poor indicator for handedness. Nonetheless, we found that another non-genetic factor, prematurity, could lead to atypical development of handedness.     

When and how norm violators gain influence: Dominance,prestige, and the social dynamics of (counter)normative behavior

The capacity to influence other people is key to success across domains of life, from personal to professional relationships, from the school yard to the retirement home, and from marketing to politics. Traditional approaches hold that people can gain influence in social collectives by behaving in line with prevailing norms. However, mounting evidence indicates that defying norms can enhance one's power, status, and influence. Here, I take stock of this literature and propose a new perspective that can explain seemingly inconsistent links between norm violation and influence. After discussing various social mechanisms that keep norm violators in check (negative emotions, gossip, social exclusion, formal punishment), I review evidence that violating norms can enhance the capacity for influence. I then integrate insights from the dominance/prestige framework of social rank with research on social responses to norm violations to develop a new model that illuminates when and how norm violators gain influence. I discuss implications for understanding the dynamic negotiation of leadership and influence and the maintenance versus decline of normative systems.     

Preattentive control of serial auditory processing in dichotic listening

Dichotic listening performance was examined in an auditory selective attention task where subjects responded to occasional consonant-vowel (CV) or shaped broadband noise-burst (NB) targets in rapid serial auditory presentation (RASP). Trial types were randomized and included monaural CVs and NBs as well as dichotic CV-CV and CV-NB pairings. CVs were spoken by two different voices (male and female), and the two NB stimuli differed in their filter slopes at higher frequencies. The target was designated by stimulus category (/ba/, /da/, /ga/, or NB) and voice (e.g., "female /ba/"). Performance was compared for targets in the left and right ears on monaural and dichotic trials using accuracy and reaction time (RT) measures. Right ear advantages (REAs) were present for CV targets with either CV or NB distractors, but not for monaural CVs. The REA found for monaural NB targets was eliminated by CV distractors, yielding a left ear advantage (LEA) for the distractor effect of CVs on NB targets. The pattern of results suggests initial preprocessing of speech stimuli through phonetic feature analysis, followed by serial attentional processing of the objects in the auditory field. REAs are attributed to a rightward asymmetry in the preattentive control of auditory attention similar to that found in visual search.     

Who Is to Blame? Official Discourse and Ethnic Diversity Attitudes During the 2011 Riots in England

In 2011, the killing of a Black man by a police officer triggered violent riots across England. In a context where ethnic minorities are rarely openly blamed, we examined the lens through which the events were interpreted in the official discourses of the British Prime Minister. A thematic content analysis (Study 1) revealed that, without explicitly blaming ethnic minorities, the discourses built on antagonistic normative references opposing a virtuous majority to threatening minorities. Then, based on online survey data of self‐declared Londoners (N = 223) during the riots, we analyzed (Study 2) how agreement with the discourses related to individuals’ ethnocentrism and their understanding of the causes underlying the events. Results of regression analyses showed how agreement with the discourses related to blaming ethnic diversity for the riots and to higher ethnocentrism, especially among individuals least likely to discriminate against minorities (i.e., low in social dominance orientation). Agreement with the discourses was also linked to reduced blame of authorities. To conclude, we discuss the mobilization potential of political discourses on ingroup virtue and outgroup threat.