Discrete Trial Research Articles

Individual differences in timing of discrete and continuous movements: a dimensional approach

This study investigated aspects of individual differences in timing of continuous and discontinuous movements to different pacing signals (auditory or visual), pacing intervals (500, 650, 800, 950 ms), and across effectors (dominant versus non-dominant hand). Correlation and principal component analysis demonstrated that a single statistical dimension accounted for up to 60% of the explained variance in discontinuous tasks and 25% of the variance in continuous tasks, when applied to performance obtained from tasks conducted with different effectors and at different pacing rates. Correlation analysis of factor scores representing effector and rate independent task performances showed that timing of discrete or continuous movements can be associated with modality independent mechanisms. Timing variability from discrete and continuous trials was not significantly correlated. This study goes beyond previous correlational work on individual differences in discrete and continuous movements, demonstrating that individual differences in discrete (event-based) or continuous (emergent) motor timing tasks can be modeled as distinctive statistical components with dissimilar capability to capture effector, rate, and modality independent variance.

Adolescent risk taking, dopamine signaling, and cocaine self-administration: a vicious cycle

Risky Decision-making Task: Male Long-Evans rats (age P25, n=54) were trained in the Risky Decision-making Task in standard behavioral test chambers. Each session in the task was 40 min in duration and consisted of 5 blocks of discrete trials, on each of which rats could choose between one of two response levers. A press on one lever resulted in delivery of one food pellet (the small, safe reward). A press on the other lever resulted in delivery of three food pellets (the large reward); however selection of this lever was also accompanied by a possible 1 s footshock (0.35 mA) contingent on a preset probability specific to each trial block (0, 25, 50, 75, and 100%, respectively). Prior to cocaine self-administration, rats were trained on the task for 25 sessions to achieve stable performance. A subgroup of rats (n=12) were sacrificed at this time point, and were prepared for in situ hybridization.

Training domestic dogs (Canis lupus familiaris) on a novel discrete trials odor-detection task

Dogs can be trained to reliably detect a wide variety of odors. Little scientific research, however, has been published on the rate at which dogs can learn to detect an odor, the variables influencing this rate, and how this rate may vary across dogs. In two experiments, we developed a procedure that allows the study of individual differences in the acquisition of an odor detection task in dogs. We demonstrate that differential reinforcement can be used to train a rooting response in a bin under the control of a novel odorant in discrete trials. In initial testing, we showed that as a group, twenty dogs performed significantly above chance within 24 trials, with two dogs meeting an individual criterion for above chance performance. In a follow-up experiment, we compared burying accessible food inside the target bin (with inaccessible food in the non-target bin) to the experimenter delivering food by hand following correct responses. We assessed the effect of this procedural variation on both an odor discrimination and a visual discrimination. Dogs learned faster on the odor task when the experimenter delivered food, compared to when food was placed directly in the bins. Performance on the visual task was lower than on the odor task and was unaffected by how food was delivered. Our discrete-trials procedure with experimenter-delivered food may be a useful method to study rapid acquisition of an odor-detection in dogs.

Effects of conducting peer behavioral observations on the observer's correct use of discrete trial teaching procedures

A procedure consisting of peer observation and evaluation termed behavioral observations was used to improve educational staff's correct use of discrete trial teaching procedures (DTT). All participants had been previously trained and proficient in using DTT procedures; however, during baseline, showed a low level of correct demonstration of DTT procedures (mean scores: 38.3%, 43.3%, and 35.0%). Participants were then taught use a checklist to observe and score a peer's performance during DTT sessions in a classroom setting. After conducting behavioral observations, staff increased their correct usage of DTT procedures to 85.1%, 88.3%, and 81.1% respectively. These data indicate that conducting behavioral observations can lead to large and rapid improvements in educational staff's correct use of DTT procedures with a large effect size (d=4.19).

Structural awareness mitigates the effect of delay in human causal learning

Many studies have demonstrated that reinforcement delays exert a detrimental influence on human judgments of causality. In a free-operant procedure, the trial structure is usually only implicit, and delays are typically manipulated via trial duration, with longer trials tending to produce both longer experienced delays and also lower objective contingencies. If, however, a learner can become aware of this trial structure, this may mitigate the effects of delay on causal judgments. Here we tested this "structural-awareness" hypothesis by manipulating whether response-outcome contingencies were clearly identifiable as such, providing structural information in real time using an auditory tone to delineate consecutive trials. A first experiment demonstrated that providing cues to indicate trial structure, but without an explicit indication of their meaning, significantly increased the accuracy of causal judgments in the presence of delays. This effect was not mediated by changes in response frequency or timing, and a second experiment demonstrated that it cannot be attributed to the alternative explanation of enhanced outcome salience. In a third experiment, making trial structure explicit and unambiguous, by telling participants that the tones indicated trial structure, completely abolished the effect of delays. We concluded that, with sufficient information, a continuous stream of causes and effects can be perceived as a series of discrete trials, the contingency nature of the input may be exploited, and the effects of delay may be eliminated. These results have important implications for human contingency learning and in the characterization of temporal influences on causal inference.

Estradiol as a Mechanism for Sex Differences in the Development of an Addicted Phenotype following Extended Access Cocaine Self-Administration

Women progress more rapidly after initial cocaine use to addiction as compared with men. Similarly, female rats appear to require less cocaine exposure before developing an addicted phenotype with evidence implicating estradiol as a potential mechanism. The goals of this study were to determine whether there are sex differences in the magnitude of the addicted phenotype under optimized conditions that induce its development in both males and females and to determine the role of estradiol in this effect. Following acquisition, intact male and intact and ovariectomized (OVX) female rats with and without estradiol replacement were given access to cocaine (1.5 mg/kg per infusion) under either extended access (ExA; discrete trial procedure, 4 trials/h, 24 h/day, 10 days) or short access (ShA) conditions (20 infusions maximum/day, 3 days). Motivation to obtain cocaine (0.5 mg/kg/infusion), as assessed under a progressive-ratio schedule, was then examined following a 2-week abstinence period. Results showed that following ExA self-administration, both males and females developed an addicted phenotype, with 9 of 11 males and 8 of 10 females showing a greater than 15% increase in levels of motivation to obtain cocaine as compared with ShA controls. In contrast, within the OVX groups, responding was enhanced from control levels after ExA self-administration in estradiol-replaced rats only. These results suggest that while females may have an enhanced vulnerability to developing an addicted phenotype, they may be similar to males once addiction has developed. These results also suggest that estradiol is critically involved in the development of an addicted phenotype in females.

Autism Research and Services for Young Children: History, Progress and Challenges

For three decades after Leo Kanner's first clinical description, research progress in understanding and treating autism was minimal but since the late 1960s the growth of autism discoveries has been exponential, with a remarkable number of new findings published over the past two decades, in particular. These advances were made possible first by the discovery and dissemination of early intensive behavioural intervention (EIBI) for young children with autism that created the impetus for earlier accurate diagnosis. Other factors influencing the rapid growth in autism research were the first accepted diagnostic test for autism, the Autism Diagnostic Interview and Observation Schedule (ADI and ADOS). Developments in brain imaging and genetic technology combined to create a fuller understanding of the heterogeneity of autism, its multiple aetiologies, very early onset and course, and strategies for treatment. For a significant proportion of children with autism, it appears EIBI may be capable of promoting brain connectivity in specific cerebral areas, which is one of autism's underlying challenges. Disagreements about the most appropriate early intervention approach between developmental and behavioural psychologists have been unproductive and not contributed to advancing the field. Naturalistic behavioural and structured discrete trial methods are being integrated with developmental strategies with promising outcomes. Over these past 30years, young people with autism have gone from receiving essentially no proactive treatment, resulting in lives languishing in institutions, to today, when half of children receiving EIBI treatment subsequently participate in regular classrooms alongside their peers. The future has entirely changed for young people with autism. Autism has become an eminently treatable condition. The time is overdue to set aside philosophical quarrels regarding theories of child development and apply what we know for the benefit of children with autism and their families.

Training Novice Instructors to Implement Errorless Discrete-Trial Teaching: A Sequential Analysis

Discrete trial teaching (DTT) is a common instructional method incorporated into intensive behavioral intervention programs for children diagnosed with autism. Errorless learning strategies are frequently recommended during DTT because they often result in more efficient and effective instruction. The purpose of the present study was to conduct a sequential analysis of the efficacy of three methods for teaching errorless DTT procedures to novice instructors: (a) a self-instruction manual, (b) an instructional video, (c) and brief performance feedback. Three participants mastered DTT following self-instruction and the remaining three participants required all three interventions. The present study extends the literature on training DTT skills by (a) illustrating an efficient, sequential method of staff training, (b) introducing an improved self-instruction manual, and (c) clearly delineating guidelines for implementing an errorless prompt fading strategy during DTT.

Teaching receptive discriminations to children with autism: a comparison of traditional and embedded discrete trial teaching.

Discrete trial teaching (DTT) procedures have proven effective in teaching language to children with autism. Discrete trial teaching uses a highly structured, fast-paced format of instruction that is typically conducted in a one-to-one situation at a desk or table with minimal distractions. We compared this traditional model of DTT to a version of DTT in which instruction was embedded within the context of a more naturalistic, activity-based environment. However, all of the other characteristics of DTT (e.g., pacing, tight stimulus control, targets selected by the teacher) were retained. Receptive discriminations were taught to 2 4-year-old boys, diagnosed with autism in traditional or embedded DTT. Results showed that for both boys, traditional and embedded DTT were equally effective and efficient. Additionally, measures were collected on participant affect and a concurrent-chains preference evaluation was used to determine which teaching procedure was preferred by the participants. The two procedures produced similar levels of positive and negative affect and were equally preferred by 1 participant while embedded DTT produced more positive affect and was more preferred by the other.

Realistic Mathematics Approach, Mathematical Communication and Problem- Solving Skills of High- Functioning Autistic Children: A Case Study

Abstract - This study involved an investigation of the effectiveness of the Realistic Mathematics Education (RME) approach in developing mathematical communication and problem-solving skills of six children diagnosed with autism but classified as high - functioning. This research-based instructional pedagogy based upon real life experiences was implemented over the course of two months. The A-B-A Single-Subject research design was employed using the principles of discrete trial training to mark the students’ progress. Two data sets were analyzed - the first data consisted of pre and posttest performance of the students evaluated using a rubric. The second data consisted of baseline, intervention and post –intervention performance of the students collected through recorded video clips and classroom observation forms. The six subjects were observed under the baseline condition until the dependent variable stabilized. Then the experimental treatment, three lessons using RME approach, were introduced by the teacher participants and the subjects were again observed to determine whether a change occurred in the mathematics communication skills and the problem-solving skills of the children after the implementation of the approach. The study showed that the training of teachers and the exposure of the students to the RME approach led to an improvement of the students’ ability to communicate mathematically and solve problems meaningfully. Keywords - RME Approach, High-Functioning Autism, Mathematical Communication, Problem-Solving Skills.

A COMPARISON OF DISCRETE TRIAL TEACHING IMPLEMENTED IN A ONE‐TO‐ONE INSTRUCTIONAL FORMAT AND IN A GROUP INSTRUCTIONAL FORMAT

Discrete trial teaching (DTT) is a systematic form of intervention commonly implemented with children and adolescents diagnosed with autism spectrum disorder. Experimenters and clinicians have implemented DTT in both one‐to‐one instructional formats and group instructional formats to teach a wide variety of skills to children and adolescents diagnosed with autism spectrum disorder. The purpose of this study was to compare DTT implemented in a one‐to‐one instructional format with DTT implemented in a group instructional format in order to determine which format was more effective, efficient, resulted in higher observational learning, and resulted in better maintenance when teaching a variety of expressive skills. The experimenters utilized a parallel treatment design, and the results indicated that both instructional formats were equally effective, there were mixed results in terms of maintenance and efficiency, and group instruction resulted in observational learning. Copyright © 2012 John Wiley & Sons, Ltd.

Training New Instructors to Implement Discrete Trial Teaching Strategies With Children With Autism in a Community-Based Intervention Program

The effects of training and supervision on instructor knowledge and performance of discrete trial teaching (DTT) within three domains (DTT Technical Skills; Work Session Preparation/Conclusion; and Student Engagement/Management) were examined in this study. Eight undergraduate student instructors received an 8-hr training in DTT and support skills accompanied by a pre- and post-test of knowledge. The instructors then taught a variety of skills to six students with autism in a community-based preschool, where instructor competence was tracked and performance feedback provided using the Discrete Trial Teaching Competency Checklist for Instructors. Competence in all three domains improved over time with performance feedback. However, significant variability was observed within and between instructors, and performance in some areas remained below optimal levels even with regular supervision and performance feedback. Implications for training and supervising instructors to implement DTT with children with autism in community-based settings are discussed.

The Effect of Noncontingent Positive Versus Negative Reinforcement on Multiply Controlled Behavior During Discrete Trial Training

Challenging behaviors with multiple functions are often difficult to treat as function-based treatments may interfere with one another. Noncontingent reinforcement may be one efficient and effective means of treating multiply controlled behavior. The purposes of this study were to compare the use of noncontingent tangible reinforcement (NCT) to noncontingent escape (NCE) with two young children with autism who engaged in multiply controlled challenging behavior. Second, we wished to examine the effect of NCT and NCE on compliance during discrete trial training. A reversal design with an embedded alternating treatment design was used to compare NCT and NCE. The NCT treatment resulted in greater reductions of challenging behavior than the NCE treatment for both participants. Compliance during discrete trial training increased under both NCT and NCE treatments.

α4β2∗ and α7 nicotinic acetylcholine receptor binding predicts choice preference in two cost benefit decision-making tasks

Nicotinic receptors have been linked to a wide range of cognitive and behavioral functions, but surprisingly little is known about their involvement in cost benefit decision making. The goal of these experiments was to determine how nicotinic acetylcholine receptor (nAChR) expression is related to two forms of cost benefit decision making. Male Long Evans rats were tested in probability- and delay-discounting tasks, which required discrete trial choices between a small reward and a large reward associated with varying probabilities of omission and varying delays to reward delivery, respectively. Following testing, radioligand binding to α4β2∗ and α7 nAChR subtypes in brain regions implicated in cost benefit decision making was examined. Significant linear relationships were observed between choice of the large delayed reward in the delay discounting task and α4β2∗ receptor binding in both the dorsal and ventral hippocampus. Additionally, trends were found suggesting that choice of the large costly reward in both discounting tasks was inversely related to α4β2∗ receptor binding in the medial prefrontal cortex and nucleus accumbens shell. Similar trends suggested that choice of the large delayed reward in the delay discounting task was inversely related to α4β2∗ receptor binding in the orbitofrontal cortex, nucleus accumbens core, and basolateral amygdala, as well as to α7 receptor binding in the basolateral amygdala. These data suggest that nAChRs (particularly α4β2∗) play both unique and common roles in decisions that require consideration of different types of reward costs.

Comparison of computer based instruction to behavior skills training for teaching staff implementation of discrete-trial instruction with an adult with autism

In the current study, behavior skills training (BST) is compared to a computer based training package for teaching discrete trial instruction to staff, teaching an adult with autism. The computer based training package consisted of instructions, video modeling and feedback. BST consisted of instructions, modeling, rehearsal and feedback. Following training, participants were evaluated in terms of their accuracy on completing critical skills for running a discrete trial program. Six participants completed training; three received behavior skills training and three received the computer based training. Participants in the BST group performed better overall after training and during six week probes than those in the computer based training group. There were differences across both groups between research assistant and natural environment competency levels.

The Effect of Video Game Play on Performance in a Vigilance Task

Traditional vigilance research typically employs static stimuli presented in discrete trials within a highly structured laboratory setting with few similarities to operational environments. The current study employs a dynamic video game-based environment in which the vigilance task has crucial elements of real world detection tasks, in this case the detection of improvised explosive devices (IEDs). The novel platform for this vigilance task and its similarity to popular video games on the market motivated the current study to compare performance between video game players (VGPs), to non-video game players (NVGPs). The results indicate that, relative to NVGPs, VGPs achieved improved performance on the vigilance task, regardless of whether they received training using knowledge of results (KR).

Attentive and pre-attentive processes in change detection and identification.

In studies of change blindness, observers often have the phenomenological impression that the blindness is overcome all at once, so that change detection, localization and identification apparently occur together. Three experiments are described that explore dissociations between these processes using a discrete trial procedure in which 2 visual frames are presented sequentially with no intervening inter-frame-interval. The results reveal that change detection and localization are essentially perfect under these conditions regardless of the number of elements in the display, which is consistent with the idea that change detection and localization are mediated by pre-attentive parallel processes.In contrast, identification accuracy for an item before it changes is generally poor, and is heavily dependent on the number of items displayed. Identification accuracy after a change is substantially better, but depends on the new item's duration. This suggests that the change captures attention, which substantially enhances the likelihood of correctly identifying the new item. However, the results also reveal a limited capacity to identify unattended items. Specifically, we provide evidence that strongly suggests that, at least under these conditions, observers were able to identify two items without focused attention. Our results further suggest that spatial pre-cues that attract attention to an item before the change occurs simply ensure that the cued item is one of the two whose identity is encoded.

Joint attention intervention for young children with autism and their parents: Combined discrete trial and milieu teaching approaches

Joint attention intervention for young children with autism and their parents: Combined discrete trial and milieu teaching approaches

Comparing Spoken Language Treatments for Minimally Verbal Preschoolers with Autism Spectrum Disorders

Preschoolers with severe autism and minimal speech were assigned either a discrete trial or a naturalistic language treatment, and parents of all participants also received parent responsiveness training. After 12 weeks, both groups showed comparable improvement in number of spoken words produced, on average. Approximately half the children in each group achieved benchmarks for the first stage of functional spoken language development, as defined by Tager-Flusberg et al. (J Speech Lang Hear Res, 52: 643-652, 2009). Analyses of moderators of treatment suggest that joint attention moderates response to both treatments, and children with better receptive language pre-treatment do better with the naturalistic method, while those with lower receptive language show better response to the discrete trial treatment. The implications of these findings are discussed.

Stability of sparse space-time finite element discretizations of linear parabolic evolution equations

The abstract linear parabolic evolution equation is formulated as a well-posed linear operator equation for which a conforming minimal residual Petrov–Galerkin discretization framework is developed: the approximate solution is defined as the minimizer of a suitable functional residual over the discrete test space, and may be obtained numerically from an equivalent algebraic residual minimization problem. This approximate solution is shown to be well defined and to converge quasi-optimally in the natural norm if the discrete trial and test spaces are stable, i.e., if the discrete inf–sup condition is satisfied with a uniform positive lower bound. For the parabolic operator we devise an abstract criterion for the stability of pairs of space–time trial and test spaces, and construct hierarchic families of trial and test spaces of a sparse space–time tensor-product type that satisfy this criterion. The theory is applied to the concrete example of the diffusion equation and is illustrated numerically.