Comparison of constant time delay and the system of least prompts in teaching preschoolers with developmental delays.

This investigation compared the effectiveness and efficiency (sessions, errors, percent of errors, and minutes of instructional time through criterion) of constant time delay and the system of least prompts in teaching sight words to developmentally delayed preschoolers. Maintenance of sight words and generalization across instructors and materials were assessed. Also, students' acquisition of relationships between the target behavior and previously learned information were assessed. Two sessions were conducted each day in their classroom, one with each procedure. Two of the children were taught 16 words and one child learned 12 words. The parallel treatments design was used to assess the effectiveness of the two instructional strategies. The results indicated that (a) both strategies produced criterion level responding in the instructional setting, (b) constant time delay resulted in fewer total trials, errors, percent of errors, and minutes of direct instructional time through criterion than the system of least prompts, (c) both strategies produced criterion-level responding that maintained in 1-, 3- and 5-week follow-up probes, (d) both strategies resulted in generalization across instructors and materials, and (e) both strategies resulted in cross-modal generalization from expressive to receptive, receptive and expressive identification of the words' function or action, and matching the written word to a photograph of its referent.     

A comparison of procedures in teaching self-help skills: Increasing assistance,time delay,and observational learning

The effectiveness and efficiency of two prompt-fading procedures were compared during the instruction of two self-help skills to four pairs of developmentally delayed preschoolers. In addition, the effect of observational learning was examined. Within a combined multiple probe and parallel treatments design, one member of each pair received direct instruction on the two skills. One skill was taught using an increasing assistance prompting procedure and the other skill was taught using a constant time delay procedure. The other member of the pair was prompted to observe the instruction, but was not taught directly. Reliability of scoring and procedural integrity were estimated, and social validity of outcomes considered. Findings indicated a slight but discernible advantage of using the time delay procedure rather than the increasing assistance procedure to teach complex, chained-response tasks. Further, considerable learning resulted solely from the observation of instruction.     

A comparison of flexible prompt fading and constant time delay for five children with autism

Given the increasing rates of autism, identifying prompting procedures that can assist in the development of more optimal learning opportunities for this population is critical. Extensive empirical research exists supporting the effectiveness of various prompting strategies. Constant time delay (CTD) is a highly implemented prompting procedure that has been researched widely, and demonstrated as effective and efficient. A second approach, flexible prompt fading (FPF) has not been empirically tested but has been a part of numerous behavioral studies [Lovaas, O. I. (1987). Behavioral treatment and normal educational and intellectual functioning in young autistic children. Journal of Clinical and Consulting Psychology, 55, 3–9; Soluaga, D., Papovich, S., Leaf, J., McEachin, J., Leaf, R., & Taubman, M. (2003). Instruction in social competencies utilizing a social skills taxonomy for persons with autism (databased presentation). Paper presented at the National Conference of the National Association for Behavior Analysis, San Francisco, CA]. The purpose of this study was to compare the effectiveness and efficiency of CTD and FPF in teaching receptive skills for five children with autism. A parallel treatment design demonstrated that, overall, the FPF procedure produced better results in terms of individual mastery of targets and global mastery of all targets and comparable results were seen in terms of efficiency for the two prompting procedures.     

A comparison of voluntary and involuntary measures of electromechanical delay

Electromechanical delay (EMD) is a measurement used to assess the mechanical lag between muscle activation onset and force production. EMD measurements may be performed by voluntary or electrically evoked muscle activation. This study compared gastrocnemius EMD during voluntary and involuntary contractions and assessd the intrasession reliability of each set of measurements. Subjects were 15 volunteers (age 21 +/- 2 years, ht 171.8 +/- 10.0 cm, mass 76.1 +/- 13.4 kg). EMD measurements were recorded from the medial head of the gastrocnemius of each subject during voluntary and involuntary contractions. Order was counterbalanced between subjects. Subjects stood with the dominant leg on a force plate, the nondominant next to the force plate, and with their hands in contact with a bar in front of them. A supramaximal percutaneous stimulus was applied to the tibial nerve in the popliteal fossa for involuntary (electrically evoked) contractions. For voluntary contractions, subjects were instructed to rise up on the toes as quickly as possible. Four trials were collected for each condition with 30 s of rest between each. Repeated measures ANOVAs were performed for each condition to calculate an ICC (2,1). Means of the 4 trials for each condition were used to detect differences between groups. EMD was greater in the voluntary condition (22.8 +/- 8.2 ms) compared to the involuntary condition (9.7 +/- 3.1 ms; p < .001). Intrasession reliability for each condition was very strong (involuntary ICC (2,1) = .977; voluntary ICC (2,1) = .972). EMD measured during a single leg stance is much shorter when measured during an electrically evoked (voluntary) contraction. The difference in EMD between conditions is likely the result of differences in recruitment during the two types of contractions. Reliability within a measurement session was very strong for each of the conditions.     

Neural correlates of implicit object identification

The present study sought to assess neural correlates of implicit identification of objects by means of fMRI, using tasks that require matching of the physical properties of objects. Behavioural data suggests that there is automatic access to object identity when observers attend to a physical property of the form of an object (e.g. the object's orientation) and no evidence for semantic processing when subjects attend to colour. We evaluated whether, in addition to neural areas associated with decisions to specific perceptual properties, areas associated with access to semantic information were activated when tasks demanded processing of the global configuration of pictures. We used two perceptual matching tasks based on the global orientation or on the colour of line drawings. Our results confirmed behavioural data. Activations in the inferior occipital cortex, fusiform and inferior temporal gyri in both tasks (orientation and colour) account for perceptual and structural processing involved in each task. In contrast, activations in the posterior and medial parts of the fusiform gyrus, shown to be involved in explicit semantic judgements, were more pronounced in the orientation-matching task, suggesting that semantic information from the pictures is processed in an implicit way even when not required by the task. Thus, this study suggests that cortical regions usually involved in explicit semantic processing are also activated when implicit processing of objects occurs.     

A comparison of the task demonstration model and the standard prompting hierarchy in teaching word identification to persons with moderate retardation

Six persons with moderate mental retardation were taught to identify three words by each of two different procedures. One, the Task Demonstration Model, was a fading procedure which relied on presenting many examples of both the correct and incorrect words while systematically increasing their similarity. The other, the Standard Prompting Hierarchy, is one of the most common procedures for teaching persons with mental retardation, and relied on a least-to-most intrusive prompting hierarchy. Data were presented in three phases and show that the Task Demonstration Model produced fewer errors in (a) acquisition (4% to 14%), (b) generalization (9% to 14%), and (c) maintenance (8% to 14%). Results were discussed in terms of the fading procedure and how the Task Demonstration Model provides a simple means for teachers to improve their students' responding in acquisition, generalization, and maintenance.     

Impaired object identification in idiopathic childhood occipital epilepsy

Purpose:: To investigate whether children with epilepsy primarily affecting the occipital cortex exhibit impairment of visual object identification and to what extent such a hypothesized dysfunction is related to an interfering functional, rather than structural, process. Method:: We studied nine children with idiopathic childhood occipital epilepsy (ICOE) and compared them to eight children with lesional posterior cortex epilepsy (PCEs) and to 60 age‐matched controls. We applied an “ascendent” paradigm of object identification, using a coarse‐to‐fine order procedure, which gradually integrated spatial frequency information from the most blurred image to the complete figure. In children with ICOE, we explored how epilepsy‐related variables might be related to object identification task. Key Findings:: Children with ICOE and those with PCEs needed more physical information than controls to identify visual stimuli. There was a decreasing accuracy from controls to children with ICOE and from children with ICOE to those with PCEs. Children with ICOE demonstrated slight selective impairment in visuospatial processing and those among them having experienced a higher number of seizures or in whom interictal electroencephalography (EEG) discharges had been present for a longer time, required a higher level of physical information to recognize objects. Significance:: The observation that children with ICOE performed worse than controls in object identification, although better than children with PCEs, might indicate that functional disruption caused by epileptiform EEG abnormalities and seizures, can interfere per se with perceptual processes, even in the absence of a lesion. This effect appears to be detected only by perceptual and cognitive screening.     

Transformation from a pure time delay to a mixed time and phase delay representation in the auditory forebrain pathway

Birds and mammals exploit interaural time differences (ITDs) for sound localization. Subsequent to ITD detection by brainstem neurons, ITD processing continues in parallel midbrain and forebrain pathways. In the barn owl, both ITD detection and processing in the midbrain are specialized to extract ITDs independent of frequency, which amounts to a pure time delay representation. Recent results have elucidated different mechanisms of ITD detection in mammals, which lead to a representation of small ITDs in high-frequency channels and large ITDs in low-frequency channels, resembling a phase delay representation. However, the detection mechanism does not prevent a change in ITD representation at higher processing stages. Here we analyze ITD tuning across frequency channels with pure tone and noise stimuli in neurons of the barn owl's auditory arcopallium, a nucleus at the endpoint of the forebrain pathway. To extend the analysis of ITD representation across frequency bands to a large neural population, we employed Fourier analysis for the spectral decomposition of ITD curves recorded with noise stimuli. This method was validated using physiological as well as model data. We found that low frequencies convey sensitivity to large ITDs, whereas high frequencies convey sensitivity to small ITDs. Moreover, different linear phase frequency regimes in the high-frequency and low-frequency ranges suggested an independent convergence of inputs from these frequency channels. Our results are consistent with ITD being remodeled toward a phase delay representation along the forebrain pathway. This indicates that sensory representations may undergo substantial reorganization, presumably in relation to specific behavioral output.     

Extra prompts versus no extra prompts in self-care training of autistic children and adolescents

A color-coded “extra prompt” procedure was compared to a “no extra prompt” procedure in teaching autistic children and adolescents how to lace shoes. One randomly assigned group of 10 autistic subjects first learned to lace shoes whose laces and eyelets were color-coded red and white, and then encountered the no extra prompt condition in which color codes could no longer be depended upon to solve the position discriminations required to lace properly. In a counterbalanced fashion, the other group of 10 autistic subjects reached criterion on the non-color-coded, naturalistic shoe before experiencing the extra prompt condition. Analysis of variance and post-hoc analyses suggest that subjects who first learned under the color-coded, extra prompt condition encountered significant difficulty in transferring their newly acquired skill to the naturalistic, non-color-coded condition, whereas subjects who learned initially without the extra prompts had little difficulty with the subsequent color-coded condition. A follow-up procedure requiring all subjects to choose between the color prompt and the position cue revealed that 11 of 20 subjects consistently chose the color cue, even though it resulted in improper lacing. It is recommended that clinicians avoid the use of highly salient, non-criterion-related prompts in teaching certain types of adaptive skills to autistic children. This research was supported by Boston University, Grant GRS 591 SAR. The authors wish to express their appreciation to the officers of Queens Services for Autistic Children and the Queens Chapter of the National Society for Autistic Children.     

A direct comparison of errorless and errorful therapy for object name relearning in Alzheimer's disease

Developing rehabilitation techniques to combat cognitive decline is a key goal of healthcare strategies aimed at promoting increased longevity and better quality of life for individuals with Alzheimer's disease (AD). In AD, problems with episodic memory and word-finding greatly affect everyday life and, as such, these symptoms provide a clear clinical target for therapeutic interventions. Errorless learning (EL) has been proposed as a particularly effective technique for relearning in individuals with memory dysfunction, including AD. However, EL learning has rarely been directly contrasted with other more traditional trial-and-error techniques (errorful learning or EF) in individuals with AD, especially in the context of alleviating word-finding problems. In the current study, we directly contrasted the therapeutic gains of an EL learning paradigm (consisting of reading/repetition of object names) with an EF learning technique (comprised of phonemic/orthographic cueing) in eight mild to moderate AD patients with pronounced anomia. Both techniques were administered concurrently in sessions run twice a week over a five-week period. Therapeutic gains were assessed at one week and five weeks post-intervention using confrontation naming. Our results suggest that, both at the group and individual patient level, EL and EF techniques were equally effective. Correlational analyses of overall therapy gains and background assessments of patient neuropsychology revealed that individuals with better scores on measures of semantic memory, pre-intervention naming, and recognition memory demonstrated larger therapy gains. No individual patient showed a significant advantage for EL over EF learning, however, for patients that showed a numerical advantage in this direction. These results suggest that either EL or EF therapy can be used to alleviate word-finding problems in AD.     

Distinctive neural mechanisms supporting visual object individuation and identification

Many everyday activities, such as driving on a busy street, require the encoding of distinctive visual objects from crowded scenes. Given resource limitations of our visual system, one solution to this difficult and challenging task is to first select individual objects from a crowded scene (object individuation) and then encode their details (object identification). Using functional magnetic resonance imaging, two distinctive brain mechanisms were recently identified that support these two stages of visual object processing. While the inferior intraparietal sulcus (IPS) selects a fixed number of about four objects via their spatial locations, the superior IPS and the lateral occipital complex (LOC) encode the features of a subset of the selected objects in great detail (object shapes in this case). Thus, the inferior IPS individuates visual objects from a crowded display and the superior IPS and higher visual areas participate in subsequent object identification. Consistent with the prediction of this theory, even when only object shape identity but not its location is task relevant, this study shows that object individuation in the inferior IPS treats four identical objects similarly as four objects that are all different, whereas object shape identification in the superior IPS and the LOC treat four identical objects as a single unique object. These results provide independent confirmation supporting the dissociation between visual object individuation and identification in the brain.     

The influence of visual and nonvisual attributes in visual object identification.

To elucidate the role of visual and nonvisual attribute knowledge on visual object identification, we present data from three patients, each with visual object identification impairments as a result of different etiologies. Patients were shown novel computer-generated shapes paired with different labels referencing known entities. On test trials they were shown the novel shapes alone and had to identify them by generating the label with which they were formerly paired. In all conditions the same triad of computer-generated shapes were used. In one condition, the labels (banjo, guitar, violin) referenced entities that were both visually similar and similar in terms of their nonvisual attributes within semantics. In separate conditions we used labels (e.g., spike, straw, pencil or snorkel, cane, crowbar) that referenced entities that were similar in terms of their visual attributes but were dissimilar in terms of their nonvisual attributes. The results revealed that nonvisual attribute information profoundly influenced visual object identification. Our patients performed significantly better when attempting to identify shape triads whose labels referenced objects with distinct nonvisual attributes versus shape triads whose labels referenced objects with similar nonvisual attributes. We conclude that the nonvisual aspects of meaning must be taken into consideration when assessing visual object identification impairments.     

A comparison of general and explicit delay cues to reinforcement for tangible-maintained challenging behaviour

Abstract

Objectives: This compares effects of explicit delay cue to reinforcement to general delay cue to reinforcement when attempting to decrease tangible-maintained challenging behaviours of children with autism spectrum disorder (ASD).

Methods: Two school-age children with ASD participated in this study. In order to evaluate the effects of a general cue versus an explicit cue on the participants’ tangibly maintained challenging behaviours, a multiple baseline design across settings with an embedded alternating treatments design was used.

Results: Results suggested that both types of delay cue to reinforcement demonstrated effectiveness on decreasing tangible-maintained behaviours of the participant. For both participants, an explicit delay cue demonstrated slightly better effects on the participants’ challenging behaviours then a general delay cue.

Conclusions: This study adds an evidence to support that delayed reinforcement can be used as an effective strategy to reduce both escape and tangible-maintained challenging behaviours of children with ASD across multiple settings.     

Similar cortical correlates underlie visual object identification and orientation judgment

Visual object perception has been suggested to follow two different routes in the human brain: a ventral, view-invariant occipital–temporal route processes object identity, whereas a dorsal, view-dependent occipital–parietal route processes spatial properties of an object. Using fMRI, we addressed the question whether these routes are exclusively involved in either object recognition or spatial representation. We presented subjects with images of natural objects and involved them either in object identification or object orientation judgment task. For both tasks, we observed activation in ventro-temporal as well as parietal areas bilaterally, with significantly stronger responses for the orientation judgment in both ventro-temporal as well as parietal areas. Our findings suggest that object identification and orientation judgment do not follow strictly separable cortical pathways, but rather involve both the dorsal and the ventral stream.     

An electrophysiological study of scene effects on object identification

The meaning of a visual scene influences the identification of visual objects embedded in it. We investigated the nature and time course of scene effects on object identification by recording event-related brain potentials (ERPs) and response times (RTs). In three experiments, participants identified objects within a scene that were either semantically congruous (e.g., a pot in a kitchen) or incongruous (e.g., a desk in a river). As expected, RTs were faster for congruous than incongruous objects. The earliest sign of reliable scene congruity effects in the ERPs (greater positivity for congruous pictures between 300 and 500 ms) was around 300 ms. Both the morphology and time course of the N390 scene congruity effect are reminiscent of the N400 sentence congruity effect typically observed in sentence context paradigms, suggesting a functional similarity of the neural processes involved. Overall, these results support theories postulating that visual scenes do not appreciably affect object identification processes before associated semantic information is activated. We speculate that the N390 scene congruity effect reflects the action of visual scene schemata stored in the anterior temporal lobe.     

时延估计在超声血流速度测量中的应用

在研究基本互相关时延估计算法的基础上,分析时延估计在血流速度估算中的原理,提出了一种非多普勒原理的间接测量血流速度的方法,通过估计时延来估计血流速度,并用实测的超声成像数据分别对10个超声回波脉冲信号和20个超声回波脉冲信号进行实验仿真,验证了通过时延估计估算血流速度的有效性,不仅能够得到较准确的血流速度值,而且方法简单,易于实现,计算量较小,具有实际的应用价值。     

Time course of processes and representations supporting visual object identification and memory

Event-related potentials (ERPs) were used to delineate the time course of activation of the processes and representations supporting visual object identification and memory. Following K. Srinivas (1993), 66 young people named objects in canonical or unusual views during study and an indirect memory test. Test views were the same or different from those at study. The first ERP repetition effect and earliest ERP format effect started at approximately 150 msec. Multiple ERP repetition effects appeared over time. All but the latest ones were largest for same views, although other aspects of their form specificity varied. Initial ERP format effects support multiple-views-plus-transformation accounts of identification and indicate the timing of processes of object model selection (frontal N350 from 148-250 to 500-700 msec) and view transformation via mental rotation (posterior N400/P600 from 250-356 to 700 msec). Thereafter, a late slow wave reflects a memory process more strongly recruited by different than same views. Overall, the ERP data demonstrate the activation of multiple memory processes over time during an indirect test, with earlier ones (within 148-400 msec) characterized by a pattern of form specificity consistent with the specific identification-related neural process or representational system supporting each memory function.     

A new notation system of object manipulation in the nesting-cup task for chimpanzees and humans

The nesting-cup task has been used to assess cognitive capability in humans as well as non-human primates. Previous studies have attempted to highlight interesting aspects of behavior by constructing and assessing various categories of manipulation. The present study introduces a new notation system for describing manipulation in nesting-cup tasks in the form of sequential codes. Following this notation, the entire process of manipulating cups can be divided into a sequence of behavioral segments. Each segment corresponds to a single manipulation of a cup, recorded as two numerical and one letter codes indicating object, location, and action, respectively. These codes describe the full extent of the subjects' manipulation, which can thus be traced retrospectively in its entirety by decoding the behavioral segments from the sequence. The subjects were three infant chimpanzees, three adult chimpanzees, and two human children. Segment-based analysis revealed developmental changes in the use of three strategies (pairing, pot, and subassembly), which previous studies have used as reliable indicators of cognitive development. Subassembly, regarded as the most advanced strategy for combining cups in human development, is defined as the placing of a previously constructed structure consisting of two or more cups into or onto another cup or cup structure. The three infant chimpanzees and two adult chimpanzees rarely showed subassembly, in contrast with frequent use by experienced adult chimpanzees and humans. Analysis of transition in cup state revealed a dynamic process in terms of progression and regression within a trial. The tendency to show progressive patterns of transition was related to the use of the subassembly strategy in both humans and chimpanzees. In addition, a case study of nine-cup manipulation by a chimpanzee is reported through sequential codes. Taken together, these data clearly demonstrate the potential of the proposed notation system in describing subjects' performance in nesting-cup tasks.     

The effect of the inter-phase delay interval in the spontaneous object recognition test for pigs

In the neuroscience community interest for using the pig is growing. Several disease models have been developed creating a need for validation of behavioural paradigms in these animals. Here, we report the effect of different inter-phase delay intervals on the performance of G?ttingen minipigs in the spontaneous object recognition test. The test consisted of a sample and a test phase. First, the pigs explored two similar objects. After a 10-min, 1-h, or 24-h delay two different objects were presented; one familiar from the sample phase and one novel. An exploration-time difference between the novel and the familiar object was interpreted as recognition of the familiar object. We scored the exploration times both manually and automatically, and compared the methods. A strong discrimination between novel and familiar objects after a 10-min inter-phase delay interval and no discrimination after 24h were found in our set-up of the spontaneous object recognition test. After a 1-h delay, the pigs still showed a significant habituation to the familiar object, but no discrimination was observed. Discrimination between the two objects was mainly confined to the first half of the test phase, and we observed a high between-subject variation. Furthermore, automatic tracking was valid for determination of habituation and discrimination parameters but lead to an overestimation of individual measurements. We conclude that the spontaneous object recognition test for pigs is sensitive to increasing inter-phase delay intervals, and that automatic data acquisition can be applied.