Generating complex three-dimensional stimuli (Greebles) for haptic expertise training

An apparatus is described that accurately measures response times and video records hand movements during haptic object recognition using complex three-dimensional (3-D) forms. The apparatus was used for training participants to become expert at perceptual judgments of 3-D objects (Greebles) using only their sense of touch. Inspiration came from previous visual experiments, and therefore training and testing protocols that were similar to the earlier visual procedures were used. Two sets of Greebles were created. One set (clay Greebles) was hand crafted from clay, and the other (plastic Greebles) was machine created using rapid prototyping technology. Differences between these object creation techniques and their impact on perceptual expertise training are discussed. The full set of these stimuli may be downloaded from www.psychonomic.org/archive/.     

Category norms for 500 Spanish words in five semantic categories

This study presents a database of 500 words from five semantic categories: animals, body parts, furniture, clothing, and intelligence. Each category contains 100 words, and data on lexical availability, age of acquisition, imageability, typicality, concept familiarity, written word frequency, and word length in number of syllables are provided with each word. The full set of norms may be downloaded from www.psychonomic.org/archive.     

Measuring Impulsivity in School-Aged Boys and Examining Its Relationship with ADHD and ODD Ratings

Seven different laboratory measures of impulsivity were administered to a group of 165 school-aged boys. Parents' and teachers' ratings of Attention Deficit and Hyperactivity Disorder and Oppositional/Defiant Disorder were also obtained. Factor analyses of impulsivity measures revealed the existence of a strong Inhibitory Control Factor including measures derived from Stop Task, the Continuous Performance Test, the Matching Familiar Figures Test, and the Circle Tracing Task. Other forms of impulsivity like resistance to interference, the Wisconsin Card Sorting Test and efficiency in the DRL Task loaded on a second independent factor. The Inhibitory Control factor was correlated with ADHD ratings, whereas the second factor was slightly related to the presence of ODD symptoms. Discussion is focused on the relevance of inhibitory control in impulsivity and ADHD research.     

Spatial learning in rats is impaired by microinfusions of protein kinase C-gamma antisense oligodeoxynucleotide within the nucleus accumbens

The nucleus accumbens (NAcc) has been shown to play a role in motor and spatial learning. Protein kinase C (PKC) has been implicated in the mechanisms of initiation and maintenance of long-term potentiation that is thought to be involved in the storage of long-term memory. In the present study, the importance of de novo synthesis of PKC-gamma within the NAcc in the acquisition and retention of spatial discrimination learning was assessed using an antisense knockdown approach. Separate groups of Long-Evans rats were exposed to acute microinfusions (6microg/microl) of PKC-gamma antisense oligodeoxynucleotide (AS-ODN), control oligodeoxynucleotide (C-ODN) or vehicle into the NAcc at 24 and 3h before each training session. Behavioral findings showed that the blockade of NAcc-PKC-gamma translation caused impairments in the early phase of learning and retention of spatial information. Biochemical experiments showed that PKC-gamma expression was reduced and Ca(2+)/phospholipid-dependent protein kinase C (PKC) activity was blocked significantly in the AS-ODN-treated rats in comparison with control rats. The present findings suggest that NAcc-PKC-gamma plays a role during the early acquisition of spatial learning. Also, retention test results suggest that NAcc-PKC-gamma may be working as an intermediate factor involved in the onset of molecular mechanisms necessary for spatial memory consolidation within the NAcc.     

Illusory conjunctions in the time domain and the resulting time-course of the attentional blink

Illusory conjunctions in the time domain are errors made in binding stimulus features presented In the same spatial position in Rapid Serial Visual Presentation (RSVP) conditions. Botella, Barriopedro, and Suero (2001) devised a model to explain how the distribution of responses originating from stimuli around the target in the series is generated. They proposed two routes consisting of two sequential attempts to make a response. The second attempt (sophisticated guessing) is only employed if the first one (focal attention) fails in producing an integrated perception. This general outline enables specific predictions to be made and tested related to the efficiency of focal attention in generating responses in the first attempt. Participants had to report the single letter in an RSVP stream of letters that was presented in a previously specified color (first target, T1) and then report whether an X (second target, T2) was or was not presented. Performance on T2 showed the typical U-shaped function across the T1-T2 lag that reflects the attentional blink phenomenon. However, as was predicted by Botella, Barriopedro, and Suero's model, the time-course of the interference was shorter for trials with a correct response to T1 than for trials with a T1 error. Furthermore, longer time-courses of interference associated with pre-target and post-target errors to the first target were indistinguishable.     

Computational approaches to the development of perceptual expertise

Dog experts, ornithologists, radiologists and other specialists are noted for their remarkable abilities at categorizing, identifying and recognizing objects within their domain of expertise. A complete understanding of the development of perceptual expertise requires a combination of thorough empirical research and carefully articulated computational theories that formalize specific hypotheses about the acquisition of expertise. A comprehensive computational theory of the development of perceptual expertise remains elusive, but we can look to existing computational models from the object-recognition, perceptual-categorization, automaticity and related literatures for possible starting points. Arguably, hypotheses about the development of perceptual expertise should first be explored within the context of existing computational models of visual object understanding before considering the creation of highly modularized adaptations for particular domains of perceptual expertise.     

The US-preexposure effect in lithium-induced flavor-aversion conditioning is a consequence of blocking by injection cues

In 2 experiments, rats received flavor-aversion conditioning in which the unconditioned stimulus (US) was an orally consumed solution of lithium chloride (LiCl). The resulting aversion was not attenuated by giving preexposure to injections of LiCl, although such preexposure did attenuate aversions established using injected LiCl as the US (Experiment 1). This outcome suggests that blocking by injection-related cues is responsible for the US-preexposure effect observed in this situation. Experiment 2 confirmed this interpretation by showing that presenting such cues (by giving an injection of saline) at the time that the LiCl was drunk resulted in an attenuation of conditioning in animals preexposed to injections of LiCl. The US-preexposure effect obtained in these experiments can be explained solely in terms of blocking by injection cues, although other mechanisms may contribute to the effect seen in other flavor-aversion paradigms.     

Pigeons use item-specific and category-level information in the identification and categorization of human faces

Three experiments examined the pigeon's ability to adapt to the specific tasks of identification and categorization of complex visual stimuli by attending to information at different levels of abstraction. In Experiment 1, pigeons were successively trained to discriminate first between pairs of human faces from the same sex and then between male and female faces. A final test revealed that the associations formed in the first training phase did not survive categorization training, indicating that the pigeons used item-specific information to discriminate faces of the same sex, but shifted their attention to category-level information for discriminating between the male and female categories. Two further experiments disproved alternative explanations. The results support the feature-learning account of open-ended categorization in animals.     

Practice variability and transfer of training: the role of self-efficacy generality

Practice variability has been shown to enhance transfer of training. The purpose of the present study was to examine the role of self-efficacy generality as a motivational mechanism in explaining the relationship between practice variability and transfer. Undergraduate students (N = 82) were randomly assigned to 1 of 2 training conditions (constant or variable) for a computer decision-making task. Measures of self-efficacy (intensity and generality) and transfer (near and far) were assessed. The results provided support for some of the hypothesized relationships. Specifically, practice variability led to increased self-efficacy generality. Both self-efficacy intensity and generality influenced far transfer performance, although only self-efficacy generality served as a mediator between practice variability and far transfer.