Cross-species differences in color categorization

Berlin and Kay (1969) found systematic restrictions in the color terms of the world’s languages and were inclined to look to the primate visual system for their origin. Because the visual system does not provide adequate neurophysiological discontinuities to supply natural color category boundaries, and because recent evidence points to a linguistic origin (Davidoff, Davies, & Roberson, 1999), a new approach was used to investigate the controversial issue of the origin of color categories. Baboons and humans were given the same task of matching-to-sample colors that crossed the blue/green boundary. The data and consequent modeling were remarkably clear-cut. All human subjects matched our generalization probe stimuli as if to a sharp boundary close to the midpoint between their training items. Despite good color discrimination, none of the baboons showed any inclination to match to a single boundary but rather responded with two boundaries close to the training stimuli. The data give no support to the claim that color categories are explicitly instantiated in the primate color vision system.     

The effects of metabolic stress and vagotomy on emotional learning in an animal model of anxiety

The aim of the present study is to evaluate the role of the blood glucose (BG) level in emotional learning in the elevated plus maze (EPM), an animal model of anxiety. In Experiment 1, male Wistar rats were submitted to different EPM trial lengths (1- or 5-min). Blood samples were withdrawn before and after the maze exploration, through a polyethylene cannula chronically implanted into the jugular vein. In Experiment 2, the animals received either saline or 2-deoxy-D-glucose, a glucoprivic drug (2-DG, 250 or 500 mg kg(-1)) by i.p. route, 30 min before a 5-min EPM exposure and were retested in the maze (Trial1/Trial2 EPM procedure) 24 h later. In an independent group of rats, blood samples were withdrawn 0, 5, 15, and 30 min after 2-DG administration, through the jugular vein, to determine BG. In Experiment 3, the animals underwent a vagotomy and were tested in a Trial1/Trial2 EPM procedure four weeks later. The results showed that rats exploring the EPM for 5 min displayed increased fear and higher hyperglycemia than those exploring the EPM for 1 min. In addition, rats submitted to 5-min EPM Trial1 length displayed higher level of fear on Trial2, as well as higher percentage of shortening of the %Open arm entries and %Open arm time from Trial1 to Trial2, which characterizes the occurrence of emotional learning. In contrast, rats previously vagotomized or treated with 2-DG (500 mg kg(-1)) showed the same level of fear on both EPM trials and a low percentage of shortening, from Trial1 to Trial2, of the %Open arm entries and %Open arm time, indicating poor emotional learning. The data is discussed regarding the role of glycaemia in emotional learning in the EPM.     

Learning under stress: how does it work?

The effects of stress on learning and memory are not always clear: both facilitating and impairing influences are described in the literature. Here we propose a unifying theory, which states that stress will only facilitate learning and memory processes: (i) when stress is experienced in the context and around the time of the event that needs to be remembered, and (ii) when the hormones and transmitters released in response to stress exert their actions on the same circuits as those activated by the situation, that is, when convergence in time and space takes place. The mechanism of action of stress hormones, particularly corticosteroids, can explain how stress within the context of a learning experience induces focused attention and improves memory of relevant information.     

Intellectual development of infants, children and adolescents with congenital heart disease

Cardiac disease is the most common congenital defect in children, affecting between 3 and 10 in every 1000 live births. While significant advances in medical and surgical management have resulted in increasing numbers of survivors, it is also recognized that there is a growing population of children living with neurological impairment and lowered intellectual function. The aetiology of such impairment is multi-factorial and hypoxia is one of the factors involved. This article provides an overview of the effects of hypoxia on the intellectual development of infants, children and adolescents with congenital heart disease.     

Letter-by-letter reading: natural recovery and response to treatment

The present investigation provides a longitudinal study of an individual (RB) with acquired alexia following left posterior cerebral artery stroke. At initial testing, RB exhibited acquired alexia characterized by letter-by-letter (LBL) reading, mild anomic aphasia, and acquired agraphia. Repeated measures of reading accuracy and rate were collected for single words and text over the course of one year, along with probes of naming and spelling abilities. Improvements associated with natural recovery (i.e., without treatment) were documented up to the fourth month post onset, when text reading appeared to be relatively stable. Multiple oral reading (MOR) treatment was initiated at 22 weeks post-stroke, and additional improvements in reading rate and accuracy for text were documented that were greater than those expected on the basis of spontaneous recovery alone. Over the course of one year, reading reaction times for single words improved, and the word-length effect that is the hallmark of LBL reading diminished. RB's response to treatment supports the therapeutic value of MOR treatment to in LBL readers. His residual impairment of reading and spelling one-year post stroke raised the question as to whether further progress was impeded by degraded orthographic knowledge.     

Conflicting visual and tactual-kinesthetic stimulation

The effects of stimulus and response probability on choice reaction time (RT) were independently investigated. In different conditions, two sets of three stimuli of probabilities of.1, .3, .6 and.3, .3, .4 were assigned to two responses-two of the stimuli assigned to one response. All combinations of S-R assignments were studied, yielding response probabilities of .1-.9, ,3-.7, and ,4-.6. With response probability held constant, variations in stimulus probability led to consistent and substantial effects on both RT and error rates. Response-probability effects were confined to error rates, and repetition effects were negligible. The results support the assumption of recent models of choice behavior that adjustments are made to the absolute (rather than just to the ordinal) values of stimulus probability.     

The Relationship Between Multicultural Counseling Training and the Evaluation of Culturally Sensitive and Culturally Insensitive Counselors

In a study, multicultural counseling training contributed significantly to the variance in ratings of a culturally sensitive counselor. No significant contribution was made to the variance in ratings of the culturally insensitive counselor. Possible explanations and implications of these results in multicultural counseling supervision are discussed.     

The role of modeling in prevention and extinction of phobic behaviour in cynomolgus monkeys (Macaca fascicularis)

In previous studies surrogate reared cynomolgus monkeys have been shown to become phobic of an unprepared harmless object. In the present study an attempt was made to prevent the development of phobic behaviour in young monkeys and to extinguish avoidance behaviour in phobic monkeys. In the first experiment subjects were exposed to the object in company of their (surrogate) mothers which approached the object. In the second experiment phobic subjects were exposed to the object in company of non-phobic conspecifics which approached the object. The results of the first experiment show that modeling was unsuccessful in preventing the acquisition of phobia in the surrogate-reared monkeys but seemed successful in accelerating approach in the mother-reared subjects. The results of the second experiment show that during the modeling treatment the phobic subjects followed the model and approached the object. However, in post treatment tests all subjects but one relapsed into avoidance. The effect of modeling during treatment is interpreted in terms of coaclive facilitation.