Effects of the premenstrual syndrome on facial expressions of sadness

This study examined the relationship between PMS and emotion-related electromyographic facial activity at different phases of the menstrual cycle. Twenty-four women of reproductive age (12 with PMS, 12 controls) participated in two EMG sessions (T1 and T2) in which they were shown photographic images that can elicit various emotions (IAPS stimuli). T1 took place in the follicular phase, T2 in the luteal phase. The activity of the musculus depressor anguli oris ("depressor", expression of sadness) was measured. Depressor activity was compared to activity of musculus orbicularis oculi ("orbicularis"; expression of joy). ANOVA yielded a significant increase of the activity of the depressor at T2 in the PMS group. The PMS group showed more frequent depressor activity during the luteal than the follicular phase. Orbicularis activity did not change from T1 to T2. Conclusions: The PMS group experienced various visual stimuli in a more depressed way during the luteal phase.     

Coordination of a discrete response with periodic finger tapping: additional experimental aspects for a subtle mechanism

The authors investigated the coordination of periodic right-hand tapping with single stimulus-evoked discrete lefthand taps to check for task interactions and a possible relationship between phase resetting (see tapping literature; e.g., J. Yamanishi, M. Kawato, & R. Suzuki, 1979) and phase entrainment (see tremor literature; e.g., R. J. Elble, C. Higgins, & L. Hughes, 1994). The experimental paradigm employs a dual-task condition as used by K. Yoshino, K. Takagi, T. Nomura, S. Sato, and M. Tonoike (2002), and it includes normal tapping and isometric tapping with the authors recording finger positions and ground contact forces. Four different types of coordination schemes were observed in tapping behavior: marginal tapping interaction (MTI), periodic tap retardation (PTR), periodic tap hastening (PTH), and discrete tap entrainment (DTE); MTI and PTR correspond to the phase-resetting effect for the coordination of periodic tapping with single discrete taps. The novel aspect of the study described in this article includes the impact of the periodic tapping on the discrete tap timing and the hastening of the periodic tapping due to the discrete tap behaviors resulting in a synchronized execution of the two concurrent tapping tasks. All participants showed a dominant tapping behavior, but they all used the other nondominant forms of the four reported coordination schemes in some trials too, which reflects possible constraints of the sensorimotor system in handling two competing tasks.     

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.