Different responses in two strains of chickens (<Emphasis Type="Italic">Gallus gallus</Emphasis>) in a magnetic orientation test

Previous studies demonstrated that layer strain domestic chicks bred for egg production can orient using directional cues from the magnetic field; here we report that chicks from a broiler strain bred for meat production do not use magnetic cues for orientation. We imprinted both strains of chicken on a red ball and subsequently trained them in a featureless testing arena. Between rewarded trials in the geomagnetic field, we inserted unrewarded tests under the following conditions: (1) in the geomagnetic field, (2) in a magnetic field with North shifted by 90 degrees and (3) in a magnetic field with the inclination inverted. The layer chicks made a correct axial response in 75-80% of the tests, shifting their choices following a rotation of magnetic North. Chicks of the broiler strain, in contrast, performed at chance level with between 47 and 60% of choices on the correct axis. This difference between the strains does not appear to be due to substantial strain differences in motivation to perform the task. It therefore appears possible that the selection of the broiler strain has led to the elimination of the specific ability to respond to magnetic cues in the test situation.     

Facets of psychopathy, Axis II traits, and behavioral dysregulation among jail detainees

Forensic evaluations of offender populations often consider psychopathy as an integral component of these consultations. Vexing issues remain of whether psychopathic traits should be evaluated consistently irrespective of demographic characteristics (e.g. gender), comorbidity (e.g. other Axis II pathology), or setting (e.g. jail or community). The current study examined gender differences for psychopathy and Axis II traits in a nonreferred jail sample of predominantly nonviolent offenders. Participants with moderate to high levels of psychopathy evidenced substantial comorbidity, especially with Cluster B personality disorders. Facets of psychopathy and Axis II traits varied substantially across both genders. In addition, the research evaluated Lynam's Hyperactivity, Impulsivity, and Attention difficulties (HIA) model of psychopathy. These initial data found little support for the HIA model in this jail sample. In testing competing hypotheses, the HIA model was substantially better at predicting Cluster B traits than psychopathy per se.     

Behavioral characterization of a transection of dorsal CA3 subcortical efferents: comparison with scopolamine and physostigmine infusions into dorsal CA3

Cholinergic projections from the medial septum and diagonal band of Broca into the hippocampus have long been implicated in learning and memory. Projections from CA3 to neurons in the medial septum and the diagonal band of Broca have been anatomically characterized. The present experiments were designed to evaluate interactions between the dorsal CA3 subcortical efferents and the cholinergic efferents from the medial septum and diagonal band of Broca for spatial and nonspatial (visual object) novelty detection in the rat. In Experiment 1, physostigmine and scopolamine (both 0.4 microL at 30 microM) were infused into dorsal CA3 and animals were tested on a spatial and nonspatial (visual object) novelty detection paradigm. Scopolamine infusions into dorsal CA3 caused deficits for both spatial and nonspatial (visual object) novelty detection. Physostigmine infusions into dorsal CA3 enhanced both spatial and nonspatial (visual object) novelty detection. These data support models proposing that acetylcholine may control the dynamics for encoding, consolidation, and retrieval in the hippocampus. In Experiment 2, a selective transection of dorsal CA3 efferents in the fimbria resulted in deficits for spatial and nonspatial (visual object) novelty detection. These deficits were similar to the deficits caused by scopolamine infusions into dorsal CA3. These data demonstrate that dorsal CA3 and the medial septum/diagonal band of Broca interact, and that dorsal CA3 influences cholinergic inputs into the hippocampus to facilitate encoding.     

Malingering on the Personality Assessment Inventory: identification of specific feigned disorders

Profile validity is a primary consideration in the clinical assessment of psychopathology. Several indicators of negative impression management have been developed for the Personality Assessment Inventory (PAI; Morey, 1991) that can both indicate its presence and help differentiate effortful negative distortion from distortion arising from cognitive sets associated with psychopathology. In this study, we tested a method designed to delineate the specific Clinical scales relevant for interpretation of deliberately feigned disorders. We used associations between the Negative Impression Management (NIM) scale and Clinical scales in the normative standardization sample to derive NIM predicted scale scores in a regression framework. We contrasted these predicted scores with observed scores on Clinical scales to yield NIM predicted discrepancies hypothesized to identify those Clinical scales most salient for the interpretation of negative distortion. We found this method to be effective in identifying particular distortion on the relevant scales for individuals attempting to feign 3 specific diagnoses (major depressive disorder, generalized anxiety disorder, and schizophrenia).     

Comparing measures of cognitive bias relating to eating behaviour

Consumption of and/or abstinence from substances with a high reward value (e.g. heroin, marijuana, alcohol, nicotine, certain foods) are associated with cognitive biases for information related to the substance. Such cognitive biases are important since they may contribute to difficulties in controlling intake of the substance. We examine cognitive biases for stimuli related to food. For the first time, we concurrently employ and compare five conceptually distinct measures of cognitive bias (dot probe, emotional Stroop, recognition, EAST, explicit attitudes). Contrary to expectations from current theory, the relation between the cognitive measures was weak and evident only in certain subsets of the population sample, as defined by gender and emotional‐, restrained‐ and external‐eating characteristics of our participants. We discuss some methodological implications of our findings. Copyright © 2008 John Wiley & Sons, Ltd.     

Chicks prefer to peck at insect-like elongated stimuli moving in a direction orthogonal to their longer axis

Spontaneous preferences towards possible prey have been little investigated using targets in motion. Preferences of domestic chicks (Gallus gallus) to peck at video-images of stimuli representing live insects moving along their longer body axis (i.e. “forwards”) or along the shorter body axis (i.e. “sideways”) were investigated. Chicks presented with both types of stimulus displayed a significant preference for pecking at stimuli moving sideways. This preference was already present on day 1 post-hatching, and it strengthened on day 6 for those chicks that had experienced pecking at live insects. Head angles used to fixate the stimuli prior to pecking were also analysed and were consistent (i.e. 30°–35° and 60°–65°) with those reported for fixation of non-edible targets (larger stimuli at a distance). In a first control experiment the same video-presented stimuli were used but the insect’s legs were removed to reduce flickering. In a second control experiment, paper-printed images of the whole insect were used. In both cases, the sideways direction of movement was clearly preferred. Overall, our data show that chicks have a spontaneous preference to peck at video-images resembling live insects moving along their shorter body axis. Sideways movement may constitute a crucial signal attracting chicks’ attention and enhancing predatory responses possibly because of stronger stimulation of motion detectors.     

Electromyographic evidence for response conflict in the exclude recognition task

How do memory retrieval processes lead to overt responses in strategic recognition tasks (responding “old” to one class of familiar stimulus and “new” to another)? Many current theories of memory retrieval ignore the response requirements in such memory tasks, instead modeling them using memory processes (e.g., familiarity and recollection) alone (see Yonelinas, 2002). We argue that strategic recognition involves conflict in response processing similar to canonical conflict tasks (e.g., the Stroop task). The parallel task set (PTS) model (Seymour, 2001) accounts for performance in strategic recognition tasks (e.g., the exclude recognition task) by suggesting that motor response conflict occurs when one responds “new” to familiar stimuli. We tested this prediction using surface electromyography, a measure incontrovertibly related to motor execution. Overall, results are consistent with the PTS model’s assumption that recognition, motor, and control processes interact in strategic retrieval tasks. The implications of these data for models of memory retrieval and response conflict are discussed.     

Effects of working memory capacity on mental set due to domain knowledge

The present set of studies examines how working memory capacity (WMC) relates to performance on a Remote Associates Task (RAT), originally designed by Mednick as a quantifiable creative problem solving assessment. The source of fixation was manipulated across two sets of RAT items. One set was neutral with no specific fixation embedded in them, while the second set was baseball-misleading, designed so that prior knowledge of baseball would lead to an incorrect solution attempt. WMC scores were positively related to performance on RAT items in all conditions, except one. High baseball knowledge participants' WMC scores did not relate to performance on the baseball-misleading RAT. While in general WMC may lead to better RAT performance, these results suggest that when there is a candidate solution strongly activated by prior knowledge, WMC may actually lead to too much focus on the incorrect solution and exacerbate mental sets.     

Affective synchrony: individual differences in mixed emotions

Most models of affect suggest either inverse or null associations between positivity and negativity. Recent work has highlighted situations that sometimes lead to mixed positive-negative affect. Focusing on the counterpart to these situational factors, the authors explore the individual-difference tendency toward mixed emotions, which they term affective synchrony. In five studies, the authors show that some individuals demonstrate affective synchrony (overlapping experience of positive and negative moods), others a-synchrony (positive and negative mood that fluctuate independently), and still others de-synchrony (positive and negative moods that function as bipolar opposites). These tendencies are stable over time within persons, vary broadly across individuals, and are associated with individual differences in cognitive representation of self and of emotions.