Interindividual-intergroup discontinuity in the domain of correspondent outcomes: the roles of relativistic concern, perceived categorization, and the doctrine of mutual assured destruction

Most prior research on the tendency for groups to be less cooperative than individuals (the interindividual-intergroup discontinuity effect) has used the Prisoner's Dilemma Game (PDG). Experiment 1 examined the discontinuity effect with 3 additional matrices: Chicken, Leader, and Battle of the Sexes (BOS). Unlike the PDG, these matrices are characterized by correspondence of outcomes. The discontinuity effect was significant for the PDG and Chicken matrices only. With the BOS and Leader matrices, both individuals and groups pursued outcome maximization through coordinated turn taking. Despite the lesser competitiveness, sets of interacting participants in the BOS and Leader conditions did perceive that they were 2 groups. Experiment 2 examined the discontinuity effect in 2 Chicken matrices with varying outcomes associated with mutual competition. Consistent with the doctrine of mutual assured destruction, the discontinuity effect was eliminated for the matrix in which mutual competition was associated with very low outcomes. Although concern for relative in-group standing gave rise to intergroup competition even in the domain of correspondent outcomes, such concern was constrained to the extent that it interfered with outcome maximization.     

Neuronal nitric oxide synthase gene inactivation reduces the expression of vasopressin in the hypothalamic paraventricular nucleus and of catecholamine biosynthetic enzymes in the adrenal gland of the mouse

The impact of a lifelong absence of the neuronal nitric oxide synthase (nNOS) in the neuroendocrine stress response was investigated in nNOS knockout (KO) and wild type (WT) mice under basal conditions and in response to forced swimming. In the hypothalamic paraventricular nucleus oxytocin and corticotropin-releasing-hormone mRNA levels did not differ between these genotypes under resting conditions, whereas vasopressin mRNA levels were significantly lower in nNOS KO than in WT animals. Also, in the adrenal glands basal levels of tyrosine hydroxylase protein, the rate-limiting enzyme for catecholamine biosynthesis, and of phenylethanolamine N-methyltransferase, which converts norepinephrine to epinephrine, were significantly reduced in nNOS KO mice. Plasma adrenocorticotropin, corticosterone, norepinephrine and epinephrine levels were similar in the KO and WT genotypes under resting conditions. In response to forced swimming, a similar increase in plasma adrenocorticotropin and corticosterone was observed in KO and WT animals. Stressor exposure triggered also an increased epinephrine release in WT animals, but did not significantly alter plasma epinephrine levels in KO mice. These data suggest that the chronic absence of nNOS reduces the capacity of epinephrine synthesising enzymes in the adrenal gland to respond to acute stressor exposure with an adequate epinephrine release.     

Exemplars and prototypes in natural language concepts: A typicality-based evaluation

Are natural language categories represented by instances of the category or by a summary representation? We used an exemplar model and a prototype model, both derived within the framework of the generalized context model (Nosofsky, 1984, 1986), to predict typicality ratings for 12 superordinate natural language concepts. The models were fitted to typicality ratings averaged across participants and to the typicality judgments of individual participants. Both analyses yielded results in favor of the exemplar model. These results suggest that higher-level natural language concepts are represented by their subordinate members, rather than by a summary representation.     

Exploring the mental number line: evidence from a dual-task paradigm

In a parity-judgment task smaller numbers are responded to faster with the left-hand key and vice versa for larger numbers (SNARC effect; Dehaene et al., in Journal of Experimental Psychology: General, 122, 371-396, 1993). We used the psychological refractory period paradigm involving a parity-judgment task and tone-discrimination task to address the question at which stage this effect arises. When the parity-judgment task is performed second, then we found equal SNARC effects for the short and the long SOA. According to the central bottleneck model, this indicates that the effect arises during the response-selection or execution stage. In Experiment 2 the parity-judgment task was performed first. The pattern of results indicates that the SNARC effect originates during the perceptual encoding or response-selection. Together, our results suggest that the SNARC effect originates while the response is selected.     

Reducing intergroup conflict through the consideration of future consequences

Basic social psychological research has suggested several interventions to reduce intergroup conflict. Most of these interventions, however, have been indirect and impractical to implement outside laboratory settings. Although past research has demonstrated that indirect manipulations of the consideration of future consequences reduce intergroup competition, no study of interindividual–intergroup discontinuity has tested this assumption with a direct manipulation. The present study found that when participants (individuals and members of groups) interacting in an iterated prisoner's dilemma game (PDG) were asked to predict how their opponent's choice on a second trial would be affected by their own choice on an initial trial, intergroup competition was reduced while interindividual competition remained low regardless of the manipulation. On a practical level, implications of this study provide a simple and easily implemented solution to reducing intergroup conflict in non‐laboratory situations. Copyright © 2009 John Wiley & Sons, Ltd.     

Inherent emotional quality of human speech sounds

During much of the past century, it was widely believed that phonemes—the human speech sounds that constitute words—have no inherent semantic meaning, and that the relationship between a combination of phonemes (a word) and its referent is simply arbitrary. Although recent work has challenged this picture by revealing psychological associations between certain phonemes and particular semantic contents, the precise mechanisms underlying these associations have not been fully elucidated. Here we provide novel evidence that certain phonemes have an inherent, non-arbitrary emotional quality. Moreover, we show that the perceived emotional valence of certain phoneme combinations depends on a specific acoustic feature—namely, the dynamic shift within the phonemes' first two frequency components. These data suggest a phoneme-relevant acoustic property influencing the communication of emotion in humans, and provide further evidence against previously held assumptions regarding the structure of human language. This finding has potential applications for a variety of social, educational, clinical, and marketing contexts.