The course of anhedonia during 10 years of schizophrenic illness

Although anhedonia has been proposed to be a trait-like characteristic in schizophrenia patients, its persistence and stability have not been tested using multiple assessments over a multiyear period. Specific definitions of anhedonia vary across studies, and relationships between different types of anhedonia as well as their relationship to schizophrenic symptoms over the course of illness have not been addressed. The current research, using prospectively collected longitudinal data covering a 10-year span for 127 individuals with schizophrenic illness, found that (a) physical, but not depressive, anhedonia is a stable characteristic over a 10-year period; (b) physical anhedonia does not show strong and consistent relationships with psychotic, negative, or depressive symptoms; and (c) the relationship between some premorbid characteristics and physical anhedonia are significant even 10 years into the course of illness.     

Understanding the relations among gender,disinhibition, and disruptive behavior in adolescents

This study examined whether disinhibition shows similar relations with attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD) symptomatology among male and female adolescents. The mixed-incentive or punishment condition of Newman's go/no-go task was administered to 172 adolescents. As expected, ADHD symptoms in boys and girls were predictive of disinhibition (i.e., commission errors) in the mixed-incentive but not punishment condition. Also consistent with expectations, CD symptoms in boys were predictive of disinhibition in the mixed-incentive but not punishment condition. In contrast, CD symptoms in girls were not predictive of disinhibition in either condition. These findings are discussed in terms of implications for understanding sex differences in the etiology of ADHD and CD.     

Locus of inhibition in the masked priming of response alternatives

Masked prime stimuli presented immediately before target stimuli in a choice reaction task give rise to behavioral costs when the primes and the target stimuli are mapped to the same response and result in benefits when they are mapped to opposite responses. Researchers assume that this negative compatibility effect reflects inhibitory processes in the control of perceptuomotor links. The authors investigated whether the inhibition operates at the level of abstract central codes or at effector-specific motor stages. In 2 experiments (N = 8 participants in each), left or right hand or foot responses were required to target stimuli that were preceded by masked arrow primes mapped to the same response side as the target stimuli in compatible trials and to the opposite response side in incompatible trials; the primes were irrelevant in neutral trials. In Experiment 1, when the masked primes determined both response side and modality, there was no transfer of negative compatibility effects across response modalities. That finding is inconsistent with a central abstract locus of inhibition and suggests that inhibition operates at effector-specific motor stages. In Experiment 2, primes conveyed only response side information but left response modality uncertain, and negative compatibility effects were elicited for both hand and foot responses, suggesting that partially informative masked primes can trigger a parallel activation and subsequent inhibition of response processes within separate effector systems.     

Context and the interpretation of likelihood information: the role of intergroup comparisons on perceived vulnerability

Four experiments investigated how people's perceptions about a group's (e.g., women's) vulnerability to a disease are influenced by information about the prevalence of the disease in a comparable group (e.g., men). Participants read symptom and prevalence infomation about fictitious diseases before answering questions regarding target group vulnerability. Participants used the prevalence rate for a nontarget group as an immediate comparison standard for intuitively interpreting the degree of vulnerability of a target group, resulting in robust contrast effects. Experiments 3 and 4 illustrated that these contrast effects can cause a person's intuitive perceptions about a group's vulnerability to selected diseases to conflict with his or her knowledge of the prevalence rates for the diseases. The results support a distinction between 2 components of psychological uncertainty-beliefs in objective probability and more intuitive perceptions of certainty.     

Ability evaluation by proxy: role of maximal performance and related attributes in social comparison

Four experiments tested the effects of information about a proxy's related attributes and maximal effort in social comparisons of ability. In Study 1, a proxy's prior performance at maximal effort exerted systematic effects on participants' personal performance predictions for a novel task. When information about the proxy's effort was ambiguous (Study 2). information about related attribute similarity was used in the formulation of performance predictions. In Studies 3 and 4, 2-way interaction terms revealed that participants used related attribute information in generating performance predictions when the proxy's maximum effort was unknown. However, related attribute information was disregarded when proxy's maximum effort was unambiguous. Results were consistent with the proxy comparison model of ability self-evaluation (L. Wheeler, R. Martin, & J. Suls, 1997).     

Derivation by prefixation in Slovenian: two aphasia case studies

The present study is concerned with two Slovenian-speaking patients who were asked to produce, in various tasks, verbs, nouns, and adjectives derived by prefixation with prepositions. Despite differences due to their specific linguistic difficulties, both patients' performance was characterized by the differential processing of prefixes and remaining components of complex words. Prepositions in prefixation were mostly preserved, and less frequently substituted, regardless of the numerous errors produced in the remaining portion of the words. These errors seem clearly determined by the morphological structure of the words and therefore appear to be authentic morphological errors. These findings contribute to the theoretical debate on mental lexical representation, speaking in favor of a morphological decomposition in processing of prefixed complex words at different processing levels.     

The effect of similarity between elemental stimuli and compounds in olfactory patterning discriminations

We studied the ability of honeybees to discriminate between single odorants and binary olfactory mixtures. We analyzed the effect of the number of common elements between these two stimulus classes on olfactory discrimination. We used olfactory conditioning of the honeybees' proboscis extension reflex (PER), a paradigm in which odors can be associated with a reinforcement of sucrose solution. Bees were asked to discriminate reinforced from nonreinforced olfactory stimuli. They were trained with two elemental odors (A and B) versus a binary olfactory mixture. The mixture was either AB (group 2CE, two common elements), AC (group 1CE, one common element A), or CD (group 0CE, no common element). Three groups followed a positive patterning schedule (mixture reinforced and elements nonreinforced: groups 2CE+, 1CE+, and 0CE+) and three other groups a negative patterning schedule (mixture nonreinforced and elements reinforced: groups 2CE-, 1CE-, and 0CE-). We showed that a reduction of similarity (number of common elements) between elemental odors and compounds enhanced the ability to discriminate elements from compounds and that the kind of compound processing used by the bees supports theories that assume nonelemental compound processing (i.e., that exclude the mere summation of the elemental associative strengths upon compound presentation).     

Spatial learning and memory is preserved in rats after early development in a microgravity environment

This study evaluated the cognitive mapping abilities of rats that spent part of their early development in a microgravity environment. Litters of male and female Sprague-Dawley rat pups were launched into space aboard the National Aeronautics and Space Administration space shuttle Columbia on postnatal day 8 or 14 and remained in space for 16 days. These animals were designated as FLT groups. Two age-matched control groups remained on Earth: those in standard vivarium housing (VIV) and those in housing identical to that aboard the shuttle (AGC). On return to Earth, animals were tested in three different tasks that measure spatial learning ability, the Morris water maze (MWM), and a modified version of the radial arm maze (RAM). Animals were also tested in an open field apparatus to measure general activity and exploratory activity. Performance and search strategies were evaluated in each of these tasks using an automated tracking system. Despite the dramatic differences in early experience, there were remarkably few differences between the FLT groups and their Earth-bound controls in these tasks. FLT animals learned the MWM and RAM as quickly as did controls. Evaluation of search patterns suggested subtle differences in patterns of exploration and in the strategies used to solve the tasks during the first few days of testing, but these differences normalized rapidly. Together, these data suggest that development in an environment without gravity has minimal long-term impact on spatial learning and memory abilities. Any differences due to development in microgravity are quickly reversed after return to earth normal gravity.     

Who is exaggerating cognitive impairment and who is not?

This chart review examined the effects of effort on neuropsychological assessment and test performance patterns among genuine and exaggerating patients, with and without neurological findings, as aids to diagnosing symptom exaggeration. The sample consisted of 561 consecutive patients involved in compensation claims. With a flexible neuropsychological test (NPT) battery, the claims were assessed over 2 days. The sample included 303 patients evaluated for traumatic brain injury, 55 patients with neurological disease, and 203 patients assessed for other conditions (eg, depression or chronic pain). An average of 38 ability measures per patient were used to generate an overall NPT domain score. Composite scores were also computed for symptom validity tests, self-report measures of psychiatric symptoms, and memory complaint inventory. Seven NPT cognitive subdomain scores were multiply regressed onto the symptom validity test composite, accounting for 45% of its total variance. Patients were also assigned to Genuine or Exaggerator groups based on symptom validity test performance. The NPT for Exaggerating patients averaged 1.43 standard deviations below that of Genuine patients, suggesting that NPT scores for most Exaggerating patients are underestimates of their true ability. Factor analysis results differed between these groups. As a result, clinicians might avoid falsely identifying genuine patients as exaggerating by incorporating their self-reports of psychiatric symptoms and memory complaints into the diagnostic process.