Timing and Foraging: Gibbon's Scalar Expectancy Theory and Optimal Patch Exploitation

We present a study that links optimal foraging theory (OFT) to behavioral timing. OFT's distinguishing feature is the use of models that compute the most advantageous behavior for a particular foraging problem and compare the optimal solution to empirical data with little reference to psychological processes. The study of behavioral timing, in contrast, emphasizes performance in relation to time, most often without strategic or functional considerations. In three experiments, reinforcer-maximizing behavior and timing performance are identified and related to each other. In all three experiments starlings work in a setting that simulates food patches separated by a flying distance between the two perches. The patches contain a variable and unpredictable number of reinforcers and deplete suddenly without signal. Before depletion, patches deliver food at fixed intervals (FI). Our main dependent variables are the times of occurrence of three behaviors: the “peak” in pecking rate (Peak), the time of the last peck before “giving in” (GIT), and the time for “moving on” to a new patch (MOT). We manipulate travel requirement (Experiment 1), level of deprivation and FI (Experiment 2), and size of reinforcers (Experiment 3). For OFT, Peak should equal the FI in all conditions while GIT and MOT should just exceed it. Behavioral timing and Scalar Expectancy Theory (SET) in particular predict a Peak at around the FI and a longer (unspecified) GIT, and make no prediction for MOT. We found that Peak was close to the FI and GIT was approximately 1.5 times longer, neither being affected by travel, hunger, or reinforcer size manipulations. MOT varied between 1.5 and just over 3 times the FI, was responsive to both travel time and the FI, and did not change when the reinforcer rate was manipulated. These results support the practice of producing models that explicitly separate information available to the subject from strategic use of this information.     

Assault victimization and suicidal ideation or behavior within a national sample of U.S. adults

Data from a nationally representative sample of 5,238 U.S. adults were used to examine the extent to which physical assault victimization was associated with suicidal ideation or behavior (SIB). The results from multivariable logistic regression analyses indicate that physical assault victimization was positively associated with SIB after adjusting for sociodemographic characteristics and alcohol use (OR = 3.6; 95% CI = 2.4-5.5). Those who were injured during the most recent physical assault (OR = 2.7; 95% CI = 1.2-6.0) and those who were assaulted by a relative (OR = 3.4; 95% CI= 1.0-11.0) or intimate partner (OR = 7.7; 95% CI = 2.7-22.5) were significantly more like to report SIB than victims who were not injured or were assaulted by a stranger. Also, those who were victimized but not injured (OR = 5.6; 95% CI = 3.8-8.2) and those who were victimized by a stranger (OR = 2.9; 95% CI = 1.4-6.0) were more likely to report SIB than non-victims. These results highlight the need for legal, medical, mental health, and social service providers to address the co-occurrence of violent victimization and suicidal ideation, particularly, but not exclusively, victimization by family members and intimates.     

Dependency,impulsivity, and self-harm: traits hypothesized to underlie the association between cluster B personality and substance use disorders

Cluster B personality disorders (PDs) (i.e., antisocial, borderline, histrionic, and narcissistic) typically show a high degree of comorbidity with substance use disorders (SUDs). Previous research suggests that the broad-based personality domains of Disinhibition and Negative Temperament/Neuroticism may be common factors to both types of disorders. Using a two-phase process (i.e., screening and follow-up), this study examined three lower-order personality traits (i.e., dependency, impulsivity, and self-harm) that fall within the Disinhibition and Neuroticism domains. The study evaluated the hypotheses that these traits (a) are related both to cluster B PDs and to SUDs; and (b) underlie the association between the two types of disorders. Results indicate that impulsivity and self-harm play a significant role in cluster B PDs and SUDs, as well as in their association with each other. However, dependency was not associated with either type of disorder. These results indicate that sets of individual traits can be of significant utility in understanding the comorbidity between PDs and SUDs.     

Opportunistic use of cognitive smokescreens by araneophagic jumping spiders

Little is known about how a prey species' cognitive limitations might shape a predator's prey-capture strategy. A specific hypothesis is investigated: predators take advantage of times when the prey's attention is focussed on its own prey. Portia fimbriata, an araneophagic jumping spider (Salticidae) from Queensland, is shown in a series of 11 experiments to exploit opportunistically a situation in which a web-building spider on which it preys, Zosis genicularis (Uloboridae), is preoccupied with wrapping up its own prey. Experimental evidence supports three conclusions: (1) while relying on optical cues alone, P. fimbriata perceives when Z. genicularis is wrapping up prey; (2) when busy wrapping up prey, the responsiveness of Z. genicularis to cues from potential predators is diminished; and (3) P. fimbriata moves primarily during intervals when Z. genicularis is busy wrapping up prey. P. fimbriata's strategy is effective partly because the wrapping behaviour of Z. genicularis masks the web signals generated by the advancing P. fimbriata's footsteps and also because, while wrapping, Z. genicularis' attention is diverted away from predator-revealing cues. Electronic Publication     

Emotion, plasticity, context, and regulation: perspectives from affective neuroscience

The authors present an overview of the neural bases of emotion. They underscore the role of the prefrontal cortex (PFC) and amygdala in 2 broad approach- and withdrawal-related emotion systems. Components and measures of affective style are identified. Emphasis is given to affective chronometry and a role for the PFC in this process is proposed. Plasticity in the central circuitry of emotion is considered, and implications of data showing experience-induced changes in the hippocampus for understanding psychopathology and stress-related symptoms are discussed. Two key forms of affective plasticity are described--context and regulation. A role for the hippocampus in context-dependent normal and dysfunctional emotional responding is proposed. Finally, implications of these data for understanding the impact on neural circuitry of interventions to promote positive affect and on mechanisms that govern health and disease are considered.     

Partner Violence, Social Support, and Distress Among Inner-City African American Women

This study examined the role of social support in the partner violence–psychological distress relation in a sample of African American women seeking medical care at a large, urban hospital (n = 138). Results from bivariate correlational analyses revealed that partner violence was related to lower perceived social support and greater psychological distress, and lower social support was related to more distress. Furthermore, findings based on path analysis indicated that low levels of social support helped account for battered women's increased distress. Findings point to the need for service providers to screen for partner violence in nontraditional sites, such as hospital emergency rooms, and to address the role of social support resources in preventive interventions with African American battered women.     

The Ponzo illusion affects grip-force but not grip-aperture scaling during prehension movements

Contextual cues such as linear perspective and relative size can exert a powerful effect on the perception of objects. This fact is demonstrated by the illusory effects that can be induced by such cues (e.g., the Ponzo railway track and Titchener circles illusions). Several recent studies have reported, however, that visual illusions based on such cues have little or no influence on the visuomotor mechanisms used to guide hand action. Furthermore, evidence of this sort has been cited in support of a distinction between visual perception and the visual control of action. In the current study, the authors investigated the effect of the Ponzo visual illusion on the control of hand action, specifically, the scaling of grip force and grip aperture during prehension movements. The results demonstrate that grip force scaling is significantly influenced by the Ponzo visual illusion, whereas the scaling of grip aperture is unaffected by the illusion.     

The Psychosocial Adjustment to Illness Scale--Self-Report: factor structure and item stability

The Psychosocial Adjustment to Illness Scale--Self-Report (PAIS-SR; Derogatis & Derogatis, 1990), a frequently used measure of adjustment in medically ill adults, was subjected to several exploratory factor analyses, with principal-axes factor extractions and varimax rotation procedures. The sample consisted of kidney, heart, liver, lung, and bone marrow transplant candidates (N = 280). The final analysis yielded a six-factor, 26-item instrument accounting for 59% of the variance. Coefficient alpha for the 26-item measure was .87, and internal consistency estimates for the factors ranged from .50 to .86. Strong correlations with other adjustment measures commonly used in the assessment of adults with chronic physical conditions support the validity of the PAIS-SR.