Visual functioning at various retinal illuminance levels is usually measured either by determining grating acuity as a function of light level or by determining how sensitivity to sine-wave gratings changes with retinal illuminance. The former line of research has shown that grating acuity follows a two-branch relationship with retinal illuminance, with the point of discontinuity occurring at the transition from scotopic to photopic vision. Results of the latter line of research have summarily been described as a transition from the DeVries-Rose law to Weber's law, according to which log sensitivity increases linearly with log illuminance with a slope of 0.5 over a range of low illuminances (the DeVries-Rose range) and then levels off and does not increase with further increases of illuminance (the Weber range). This paper aims at determining the compatibility of the results of these two lines of research. We consider empirical constraints from data bearing on the shape of the surface describing contrast sensitivity to sine-wave gratings as a function of spatial frequency and illuminance simultaneously, in order to determine whether they are consistent with a summary description in terms of DeVries-Rose and Weber's laws. Our analysis indicates that, with sine-wave gratings, the DeVries-Rose law can only hold empirically at low spatial frequencies.

This study researches the input of the cerebral occipital and temporal cortex in the analysis of facial configuration and expressive characteristics. Analysis is based on the construction of a spherical model for the differentiation of schematically presented faces with quantitatively altering curvature of the mouth and brows. The model is designed using the method of multidimensional scaling of the dissimilarity judgments between stimuli (faces) and the amplitude of evoked potentials of differences (EPD) between abrupt stimulus changes recorded from the occipital and posterior temporal cortex. Analysis of the structure of the spherical model of facial differentiation depending on the electrode site and the latency of the EPD component within the duration of 120-240 ms has demonstrated that the activity of the occipital and posterior temporal cortex of the right hemisphere is associated with the emotional characteristics of the presented face, whereas facial configuration is reflected in the activation of both posterior temporal cortex and the occipital cortex of the left hemisphere. At all electrode sites maximum information of the emotional expression and configuration is represented in inter-peak amplitude P120-N180. With increasing latency there is increased distortion of the structure of differences in the spherical model of schematically presented faces, which is interpreted as an attenuation of electrical activity associated with the analysis of the emotional expression, which occurs more rapidly than configuration analysis.

In the context of a medium-term study designed to integrate the simulation of different types and processes of learning—such as classical, operant, and some cognitive types—one must start with other more elementary ones that are facilitators of the more complex types and processes. Of special interest is habituation, owing to the filtering out of irrelevant stimuli, which means that the simulated agent does not have to respond to them. This paper presents two difference functions constructed to computationally simulate the characteristics that define habituation. The behavior of these functions is described, as are differences arising from stimulus intensity and interstimulus intervals. Results are compared with existing empirical data.

A new memory model is proposed based on regression analysis and exponential- shaped learning curves. The efficacy of the model is tested with several types of experiments including food aversion in snails, maze learning in rats and memory tests for adults and children. The model is also tested on drug abusers and alcoholics. The results of goodness of fit tests indicate that our model can accurately be used to predict the memory dynamics of diverse experiments and populations. The model can also be used to predict both group and individual performance. The application of the model to detect memory impairment is discussed, as are limitations.

Four experiments examined the role of meaning frequency (dominance) and associative strength (measured by associative norms) in the processing of ambiguous words in isolation. Participants made lexical decisions to targets words that were associates of the more frequent (dominant) or less frequent (subordinate) meaning of a homograph prime. The first two experiments investigated the role of associative strength at long SOAs (Stimulus Onset Asynchrony) (750 ms.), showing that meaning is facilitated by the targets' associative strength and not by their dominance. The last two experiments traced the role associative strength at short SOAs (250 ms), showing that the manipulation of the associative strength has no effect in the semantic priming. The conclusions are: on the one hand, semantic priming for homographs is due to associative strength manipulations at long SOAs. On the other hand, the manipulation of the associative strength has no effect when automatic processes (short SOAs) are engaged for homographs.

In this paper, the perspective of situated cognition, which gave rise both to the pragmatic theories and the so-called semantic theories of learning and has probably become the most representative standpoint of constructivism, is examined. We consider the claim of situated cognition to provide alternative explanations of the learning phenomenon to those of psychology and, especially, to those of the symbolic perspective, currently predominant in cognitive psychology. The level of analysis of situated cognition (i.e., global interactive systems) is considered an inappropriate approach to the problem of learning. From our analysis, it is concluded that the pragmatic theories and the so-called semantic theories of learning which originated in situated cognition can hardly be considered alternatives to the psychological learning theories, and they are unlikely to add anything of interest to the learning theory or to contribute to the improvement of our knowledge about the learning phenomenon.

This study investigated the relationships between impulsivity, intelligence, and academic failure in a sample of 241 secondary school students who completed Thurstone's (1938) Primary Mental Abilities (PMA) test and Dickman's (1990) and Barratt's (1985) impulsivity questionnaires (DII and BIS-10, respectively). Results show an inverse relationship between impulsivity and intelligence, specific to the scales with higher loadings on crystallized intelligence, and a positive relationship between impulsivity and academic failure. These results indicate that impulsivity is not directly related to intelligence and may act as a moderator variable between individuals' resources and their achievements.

Ninety-two clinic-referred and nonclinical mother-child dyads in Spain and the USA were observed in their home settings under naturalistic conditions for a total of 477 hours. Children in the clinic-referred dyads were considered troubled because of conduct problems. The observations were aimed at assessing two forms of mother-child asynchrony, either of which was expected to differentiate clinic referred from nonclinical dyads. Authoritarian asynchrony was defined as a mother's indiscriminate use of aversive reactions to her child, whereas the permissive form entailed indiscriminate positive reactions. Results showed the American mothers to generate more permissive asynchrony, whereas the Spanish mothers were inclined in the authoritarian direction. Only authoritarian asynchrony differentiated the clinical versus nonclinical dyads in each country. Discussion was centered on the greater salience of aversive as opposed to positive maternal attention, and cultural differences between countries that might have accounted for the different parenting styles.

The purpose of this work is to test the chief principle of brainstorming, formulated as “quantity generates quality.” The study is included within a broad program whose goal is to detect the strong and weak points of creative techniques. In a sample of 69 groups, containing between 3 and 8 members, the concurrence of two commonly accepted criteria was established as a quality rule: originality and utility or value. The results fully support the quantity-quality relation (r = .893): the more ideas produced to solve a problem, the better quality of the ideas. The importance of this finding, which supports Osborn's theory, is discussed, and the use of brainstorming is recommended to solve the many open problems faced by our society.

The purpose of this research is to provide information about the state of psychotherapy in Argentina, as well as to study some variables involved in psychologists' evaluation of psychotherapy. A survey of 14 items was elaborated ad-hoc for this purpose, and administered to 226 psychologists from all over the country by mail and, in some cases, personally. Results suggest that the predisposition to apply techniques from different frameworks is associated with the amount of experience and with the perception of a bias concerning other theoretical focuses, although it is not related to the evaluation of the state of psychotherapy. On the other hand, in the view of psychologists, personal aspects of the therapeutic relationship are believed to be the most important factor in patients' change and effective progress.

Twenty-four detoxified opiate addicts were randomized to an experimental group and a control group to evaluate efficacy of a group cue-exposure treatment to reduce or extinguish classically conditioned responses to drug-related stimuli. Assessment included psychophysiological responses (skin temperature, skin conductance level—SCL—, and heart rate) to a videotape and subjective measures (subjective craving, positive and negative affect) before and after the videotape. The experimental group received a group cue-exposure program to drug-related stimuli that comprised twelve treatment sessions administered three times weekly. The treatment program significantly reduced conditioned responses to drug-related stimuli, as measured by SCL and positive affect.

A grandmaster and an international chess master were compared with a group of novices in a memory task with chess and non-chess stimuli, varying the structure and familiarity of the stimuli, while functional magnetic resonance images were acquired. The pattern of brain activity in the masters was different from that of the novices. Masters showed no differences in brain activity when different degrees of structure and familiarity where compared; however, novices did show differences in brain activity in such contrasts. The most important differences were found in the contrast of stimulus familiarity with chess positions. In this contrast, there was an extended brain activity in bilateral frontal areas such as the anterior cingulate and the superior, middle, and inferior frontal gyri; furthermore, posterior areas, such as posterior cingulate and cerebellum, showed great bilateral activation. These results strengthen the hypothesis that when performing a domain-specific task, experts activate different brain systems from that of novices. The use of the experts-versus-novices paradigm in brain imaging contributes towards the search for brain systems involved in cognitive processes.

The aim of this research was to study the effect of 12-minute clinical death on innate and acquired behavior, biogenic amine concentration, and the composition and quantity of neural populations in specific brain regions of white rats. The study shows that in animals during the postresuscitation period with formal restoration of neurological status, there are changes in emotional reactivity, orientation-exploration reactions, impairment of learning and memory, decrease in exercise tolerance and pain sensitivity. These processes are accompanied by alterations in serotonin and norepinephrine levels in the frontal cerebral cortex, dopamine and serotonin levels in the striatum, certain biochemical indices in blood plasma and neural loss in the CA1 sector of the hippocampus and lateral portions of the cerebellum.

Research on estimation of a psychometric function Ψ has usually focused on comparing alternative algorithms to apply to the data, rarely addressing how best to gather the data themselves (i.e., what sampling plan best deploys the affordable number of trials). Simulation methods were used here to assess the performance of several sampling plans in yes–no and forced-choice tasks, including the QUEST method and several variants of up–down staircases and of the method of constant stimuli (MOCS). We also assessed the efficacy of four parameter estimation methods. Performance comparisons were based on analyses of usability (i.e., the percentage of times that a plan yields usable data for the estimation of all the parameters of Ψ) and of the resultant distributions of parameter estimates. Maximum likelihood turned out to be the best parameter estimation method. As for sampling plans, QUEST never exceeded 80% usability even when 1000 trials were administered and rendered accurate estimates of threshold but misestimated the remaining parameters. MOCS and up–down staircases yielded similar and acceptable usability (above 95% with 400–500 trials) and, although neither type of plan allowed estimating all parameters with optimal precision, each type appeared well suited to estimating a distinct subset of parameters. An analysis of the causes of this differential suitability allowed designing alternative sampling plans (all based on up–down staircases) for yes–no and forced-choice tasks. These alternative plans rendered near optimal distributions of estimates for all parameters. The results just described apply when the fitted Ψ has the same mathematical form as the actual Ψ generating the data; in case of form mismatch, all parameters except threshold were generally misestimated but the relative performance of all the sampling plans remained identical. Detailed practical recommendations are given.