Lateralized perceptual organization deficits on the global-local task in schizotypal personality disorder

Right and left hemisphere contributions to perceptual organization functions were examined using a divided-attention version of the global-local task in a sample of 21 unmedicated participants diagnosed with schizotypal personality disorder (SPD) and 20 controls. The SPD participants showed an abnormal global processing advantage. When the visual angle of the hierarchical stimuli was increased from 3 degrees to 9 degrees, the controls showed an increasing local processing advantage, but the SPD participants continued to show an abnormal global processing advantage. These findings suggest a local processing deficit on divided-attention versions of the global-local task in schizophrenia spectrum disorders. Female SPD participants, who had less severe interpersonal deficit symptoms, showed a more abnormal global processing advantage. Hemispheric and processing resource mechanisms that might explain these findings are discussed.     

Economic pressure in African American families: a replication and extension of the family stress model

This study of 422 two-caregiver African American families, each with a 10-11-year-old focal child (54% girls), evaluated the applicability of the family stress model of economic hardship for understanding economic influences on child development in this population. The findings generally replicated earlier research with European American families. The results showed that economic hardship positively relates to economic pressure in families. Economic pressure was related to the emotional distress of caregivers, which in turn was associated with problems in the caregiver relationship. These problems were related to disrupted parenting practices, which predicted lower positive child adjustment and higher internalizing and externalizing symptoms. The results provide significant support for the family stress model of economic hardship and its generalizability to diverse populations.     

Deaf poor readers' pattern reversal visual evoked potentials suggest magnocellular system deficits: implications for diagnostic neuroimaging of dyslexia in deaf individuals

Deafness and developmental dyslexia in the same individual may jointly limit the acquisition of reading skills for different underlying reasons. A diagnostic marker for dyslexia in deaf individuals must therefore detect the presence of a neurobiologically based dyslexia but be insensitive to the ordinary developmental influences of deafness on reading skill development. We propose that the functional status of the magnocellular visual system in deaf individuals is potentially such a marker. We present visual evoked potential (VEP) evidence that adult deaf poor readers as a group display magnocellular system deficits not observed in deaf good readers. We recorded pattern-reversal VEPs to high- and low-contrast checkerboard stimuli, which primarily activate the parvocellular and magnocellular pathways, respectively. Principal components analysis of these VEPs produced a time-ordered sequence of three early components that displayed interactions between reading skill and stimulus contrast across multiple scalp recording sites. Deaf poor readers displayed an abnormal absence of contrast-sensitive VEP responses at occipital sites during early visual processing (75 ms poststimulus), whereas deaf good readers showed the expected early contrast-sensitive occipital VEP responses. Over the subsequent 225 ms, the occipital VEP behavior of deaf poor readers closely approximated that of deaf good readers. The VEPs of deaf poor readers were apparently characterized by delayed responses to low-contrast stimuli compared with deaf good readers. Our results provide the first neurobiological evidence that developmental dyslexia exists within the deaf population and is associated with the same underlying magnocellular system deficit that has been observed in hearing dyslexics. Direct neural imaging of the status of the magnocellular visual system in deaf individuals may eventually provide differential diagnosis of developmental dyslexia in the deaf population.     

Do not prime hawks with doves: the interplay of construct activation and consistency of social value orientation on cooperative behavior

Low and high consistent pro-socials and pro-selfs were primed with neutral, morality, or might concepts in mixed-motive situations. The authors expected participants' social value orientation to influence cooperative behavior among (a) high consistent individuals in all prime conditions and (b) low consistent individuals in the neutral prime condition only. The authors also expected the primes to influence cooperative behavior more among low than high consistent individuals. Four experiments using supra-liminal (Experiments 1, 2, and 4) or subliminal (Experiment 3) priming and 2-person (Experiments 1-3) or N-person (Experiment 4) social dilemmas partially supported these initial predictions. One intriguing exception was that morality primes reduced cooperation among high consistent pro-selfs. Experiments 2-4 allowed testing for the potential role of expectations in shaping participants' cooperative behavior.     

Contribution of somesthetic cues to the perception of body orientation and subjective visual vertical

Without relevant visual cues, the subjective visual vertical (SVV) is biased in roll-tilted subjects toward the body axis (Aubert or A-effect). This study focused on the role of the somatosensory system with respect to the SVV and on whether somesthetic cues act through the estimated body tilt. The body cast technology was used to obtain a diffuse tactile stimulation. An increased A-effect was expected because of a greater underestimation of the body position in the body cast. Sixteen subjects placed in a tilt chair were rolled sideways from 0 degrees to 105 degrees. They were asked to verbally indicate their subjective body position and then to adjust a luminous line to the vertical under strapped and body cast conditions. Results showed a greater A-effect (p < .001) but an overestimation of the body orientation (p < .01) in the body cast condition for the higher tilt values (beyond 60 degrees). Since the otolith organs produced the same gravity response in both conditions, errors were due to a change in somesthetic cues. Visual and postural errors were not directly related (no correlation). However, the angular distance between the apparent body position and the SW remained stable, suggesting that the change in somatosensory pattern inputs has a similar impact on the cognitive processes involved in assessing the perception of external space and the sense of self-position.     

Focal distraction: spatial shifts of attentional focus are not required for contingent capture

Contingent capture occurs when distractors that share the target's defining attribute capture attention and slow down target identification. This slowdown has been attributed to an involuntary attentional shift to the location of a pertinent distractor. The present study examined an additional source of delay: the time spent in processing pertinent distractors. In 7 experiments, distractors were presented at fixation, and targets were presented either at fixation or peripherally. Contingent capture invariably occurred when a salient distractor was presented within about 600 ms before the target, even when spatial shifts in attentional focus were ruled out. A 2-stage model is proposed in which stimuli must pass an input filter tuned to the target's defining attribute before gaining access to a high-level stage that is unavailable while a distractor is being processed.     

Multiple serotonergic mechanisms contributing to sensitization in aplysia: evidence of diverse serotonin receptor subtypes

The neurotransmitter serotonin (5-HT) plays an important role in memory encoding in Aplysia. Early evidence showed that during sensitization, 5-HT activates a cyclic AMP-protein kinase A (cAMP-PKA)-dependent pathway within specific sensory neurons (SNs), which increases their excitability and facilitates synaptic transmission onto their follower motor neurons (MNs). However, recent data suggest that serotonergic modulation during sensitization is more complex and diverse. The neuronal circuits mediating defensive reflexes contain a number of interneurons that respond to 5-HT in ways opposite to those of the SNs, showing a decrease in excitability and/or synaptic depression. Moreover, in addition to acting through a cAMP-PKA pathway within SNs, 5-HT is also capable of activating a variety of other protein kinases such as protein kinase C, extracellular signal-regulated kinases, and tyrosine kinases. This diversity of 5-HT responses during sensitization suggests the presence of multiple 5-HT receptor subtypes within the Aplysia central nervous system. Four 5-HT receptors have been cloned and characterized to date. Although several others probably remain to be characterized in molecular terms, especially the Gs-coupled 5-HT receptor capable of activating cAMP-PKA pathways, the multiplicity of serotonergic mechanisms recruited into action during learning in Aplysia can now be addressed from a molecular point of view.     

The validity of the Antisocial Process Screening Device as a self-report measure of psychopathy in adolescent offenders

There is a growing interest in the assessment of adolescent psychopathy to enable early treatment and intervention. Recently, a self-report measure has been developed to assess psychopathic traits in adolescents. The Antisocial Process Screening Device (APSD), a self-report measure of psychopathic traits, and the Psychopathy Checklist: Youth Version (PCL:YV), a clinical rating scale, were administered to a sample of 100 incarcerated male adolescent offenders to assess the concurrent validity of the APSD. Results indicated that the APSD had limited concurrent validity with respect to the PCL:YV and that there appears to be a method effect in the measurement of psychopathy. Thus, it appears the APSD did not assess psychopathy in a manner parallel to that of the PCL:YV.     

A gray seal's (Halichoerus grypus) responses to experimenter-given pointing and directional cues

A gray seal (Halichoerus grypus) was trained to touch a target on its left or right by responding to pointing signals. The authors then tested whether the seal would be able to generalize spontaneously to altered signals. It responded correctly to center pointing and head turning, center upper body turning, and off-center pointing but not to head turning and eye movements alone. The seal also responded correctly to brief ipsilateral and contralateral points from center and lateral positions. Pointing gestures did not cause the seal to select an object placed centrally behind it. Like many animals in similar studies, this gray seal probably did not understand the referential character of these gestures but rather used signal generalization and experience from initial operant conditioning to solve these tasks.     

Task switching mediates the attentional blink even without backward masking

When two targets are presented in rapid succession, perception of the second target is impaired at short intertarget lags (100-700 msec). This attentional blink (AB) is thought to occur only when the second target is backward masked. To the contrary, we show that task switching between the targets can produce an AB even without masking (Experiments 1 and 3). Further, we show that task switching produces an AB only when the second target does not belong to a class of overlearned stimuli such as letters or digits (Experiments 1 and 4). When the second target is masked, however, an AB is invariably obtained regardless of switching or overlearning. We propose that task switching involves a time-consuming process of reconfiguration of the visual system, during which the representation of the second target decays beyond recognition, resulting in an AB deficit. We suggest that overlearned stimuli are encoded in a form that, while maskable, decays relatively slowly, thus outlasting the delay due to reconfiguration and avoiding the AB deficit.