Some effects of stimulant medication on response allocation: a double-blind analysis

Children who are diagnosed with attention deficit hyperactivity disorder (or who engage in behavior consistent with such a diagnosis) are often prescribed stimulant medications for hyperactive or inattentive behaviors. However, the mechanisms by which stimulant medications affect individuals' behavior are rarely evaluated. The purpose of the current study was to evaluate the effects of stimulant medication on response allocation when antecedents and consequences were held constant and equated. Results indicated that the presence of an amphetamine medication (Adderall) influenced response allocation across two concurrently available responses while all other stimulus conditions were held constant.     

A comparison of intra- and inter-limb relative motion information in modelling a novel motor skill

The importance of intra- and inter-limb relative motion in modelling a whole body coordination skill was examined. Participants were assigned to one of four groups: Full-Body point light model of a cricket bowler, INTRA-LIMB relative motion of the bowling arm, INTER-LIMB relative motions of the right and left wrists or NO-Relative motion, showing only the motions of the right wrist. During 60 acquisition trials, participants viewed the model five times before each 10-trial block. Retention was examined the following day. Although all groups improved on intra-limb coordination of the bowling arm, the INTRA-LIMB and FULL-BODY groups were more accurate than the INTER-LIMB group in acquisition, although these groups did not differ in retention. For inter-limb coordination, the three groups who received relative motion information performed more like the model than the NO-Relative motion group (even though the INTRA-LIMB group did not see the other limb). The amount of information within a display plays a constraining role on acquisition, perhaps more so than the type of information, such that the acquisition of coordination is more an emergent feature of observational learning, rather than a direct approximation of the model.     

The role of phonological recoding in orthographic learning

The objective of this research was to explore whether orthographic learning occurs as a result of phonological recoding, as expected from the self-teaching hypothesis. The participants were 32 fourth- and fifth-graders (mean age = 10 years 0 months, SD = 7 months) who performed lexical decisions for monosyllabic real words and pseudowords under two matched experimental conditions: a read aloud condition, wherein items were named prior to lexical decision to promote phonological recoding, and a concurrent articulation condition, presumed to attenuate phonological recoding. Later, orthographic learning of the pseudowords was evaluated using orthographic choice, spelling, and naming tasks. Consistent with the self-teaching hypothesis, targets learned with phonological recoding in the read aloud condition yielded greater orthographic learning than those learned with concurrent articulation. The research confirms the critical nature of phonological recoding in the development of visual word recognition skills and an orthographic lexicon.     

Neural modeling and imaging of the cortical interactions underlying syllable production

This paper describes a neural model of speech acquisition and production that accounts for a wide range of acoustic, kinematic, and neuroimaging data concerning the control of speech movements. The model is a neural network whose components correspond to regions of the cerebral cortex and cerebellum, including premotor, motor, auditory, and somatosensory cortical areas. Computer simulations of the model verify its ability to account for compensation to lip and jaw perturbations during speech. Specific anatomical locations of the model's components are estimated, and these estimates are used to simulate fMRI experiments of simple syllable production.     

Sound-symbolism: A Piece in the Puzzle of Word Learning

Sound-symbolism is the idea that the relationship between word sounds and word meaning is not arbitrary for all words, but rather that there are subsets of words in the world’s languages for which sounds and their symbols have some degree of correspondence. The present research investigates sound-symbolism as a possible route to the learning of an unknown word’s meaning. Three studies compared the guesses that adult participants made regarding the potential meanings of sound-symbolic and non-sound symbolic obsolete words. In each study, participants were able to generate better definitions for sound-symbolic words when compared to non-sound symbolic words. Participants were also more likely to recognize the meanings of sound symbolic words. The superior performance on sound-symbolic words held even when definitions generated on the basis of sound association were eliminated. It is concluded that sound symbolism is a word property that influences word learning.     

Age of acquisition effects in vocabulary learning

Two experiments examined whether the age of acquisition (AoA) of a concept influences the speed at which native English speakers are able to name pictures using a newly acquired second language (L2) vocabulary. In Experiment 1, participants were taught L2 words associated with pictures. In Experiment 2 a second group of participants were taught the same words associated with L1 translations. Following training both groups performed a picture naming task in which they were asked to name pictures using the newly acquired words. Significant AoA effects were observed only in Experiment 1, in that participants were faster at naming pictures representing early acquired relative to late acquired concepts. The results suggest that the AoA of a concept can exert influence over processing which is independent of the AoA of the word form. The results also indicate that different training methods may lead to qualitative differences in the nature of the links formed between words and concepts during the earliest stages of second language learning.     

Fear generalization in humans: Impact of verbal instructions

Fear generalization lies at the heart of many anxiety problems, but little is known about the factors that can influence this phenomenon. The present study investigated whether verbal instructions about specific stimulus features can influence conditioned fear generalization. All participants were fear conditioned to a yellow triangle, using an electric shock. Participants had received pre-experimental instructions saying that the shapes (or colours) of the stimuli were informative for the occurrence of shock (group Shape and group Colour, respectively). Next, generalization was tested to presentations of a blue triangle (same shape) as well as a yellow square (same colour). Fear reactions were measured through skin conductance and online ratings of shock-expectancy. The results showed strongest generalization to the same shape stimulus in group Shape, versus the same colour stimulus in group Colour. Hence, the same learning experience can have opposite effects in terms of fear generalization, depending on verbally transmitted information about the relative importance of individual stimulus features.     

An especial skill: Support for a learned parameters hypothesis

We tested the ‘learned parameters’ hypothesis as an explanation of the ‘especial skill effect’. Outcome attainment and movement kinematics were recorded for 10 expert and 10 novice players performing basketball free-throw shots at five distances (11-19 ft) with a regular and heavy weight basketball. As predicted, experts performed better than expected relative to the regression equation at the 15 ft, free-throw line with the regular basketball, supporting the ‘especial skill effect’. This effect was not present for the experts when shooting with the heavy ball. Novices did not show an advantage at the free-throw line when performing with either ball. Although the outcome attainment scores support the ‘learned parameters’ hypotheses, kinematic analysis failed to identify differences in the movement pattern for the especial skill, suggesting that these skills (i.e., shooting at different distances) are not governed by separate motor programs.     

Novel labels support 10-month-olds’ attention to novel objects

What is the source of the mutual exclusivity bias whereby infants map novel labels onto novel objects? In an intermodal preferential looking task, we found that novel labels support 10-month-olds’ attention to a novel object over a familiar object. In contrast, familiar labels and a neutral phrase gradually reduced attention to a novel object. Markman (1989, 1990) argued that infants must recall the name of a familiar object to exclude it as the referent of a novel label. We argue that 10-month-olds’ attention is guided by the novelty of objects and labels rather than knowledge of the names for familiar objects. Mutual exclusivity, as a language-specific bias, might emerge from a more general constraint on attention and learning.     

Bayesian parameter estimation in the Expectancy Valence model of the Iowa gambling task

The purpose of the popular Iowa gambling task is to study decision making deficits in clinical populations by mimicking real-life decision making in an experimental context. Busemeyer and Stout [Busemeyer, J. R., & Stout, J. C. (2002). A contribution of cognitive decision models to clinical assessment: Decomposing performance on the Bechara gambling task. Psychological Assessment, 14, 253-262] proposed an “Expectancy Valence” reinforcement learning model that estimates three latent components which are assumed to jointly determine choice behavior in the Iowa gambling task: weighing of wins versus losses, memory for past payoffs, and response consistency. In this article we explore the statistical properties of the Expectancy Valence model. We first demonstrate the difficulty of applying the model on the level of a single participant, we then propose and implement a Bayesian hierarchical estimation procedure to coherently combine information from different participants, and we finally apply the Bayesian estimation procedure to data from an experiment designed to provide a test of specific influence.