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Biomedical subjects

W K Berg

Publications and source records attributed to W K Berg.

At least 37 records · Page 2Linked to original sources
PubMed1988

An evaluation of labeling-then-doing with moderately handicapped persons: acquisition and generalization with complex tasks.

We conducted two experiments in which moderately mentally retarded persons were trained first to label and then to enter characters into a computer, calculator, or checkbook (label-then-do) within a multiple baseline design. In Experiment 1, 5 young adults were trained to enter statistical programs into computers in an office setting. Following training, all subjects' use of verbal labels and key-entry skills generalized across tasks (programs) and settings (offices and computer terminals). In Experiment 2, 3 junior high school students were trained with self-labeling procedures to complete a key-entry task and to balance a checkbook. The performance of all students generalized across tasks and settings, and the use of labels generalized for 2 of the students. Results are discussed relative to mediated generalization and to establishing verbal control over behavior.

Adolescent↗
PubMed1987

The startle response and auditory temporal summation in neonates.

The present study assessed temporal summation of transient and sustained stimuli in the startle eyeblink response system in neonates during quiet sleep. Subjects received 100-dB(A), fast-rising broadband noise bursts of two types: (a) single stimuli varying in duration from 20 to 100 ms and (b) pairs of 3-ms bursts presented at interpulse intervals corresponding to the single-stimulus durations. In addition, a single 3-ms pulse was used as an anchor point for both stimulus types. For startle amplitude, single stimuli were more effective than were paired stimuli, but the temporal summation functions were similar for the two types of stimuli. Response amplitude increased as stimulus duration/interval increased to 50 ms, but not beyond. For startle probability, temporal summation was similar for single and paired stimuli at 20 ms. Pairs of pulses were equally effective at 20, 35, and 50 ms, beyond which the second pulse was not effective. Increasing the duration of single stimuli from 20 to 35 ms resulted in increased probability, illustrating a contribution of sustained summation beyond that of transient summation. Response latency was generally greater for paired than for single stimuli. The results suggest that temporal summation of brief stimuli is deficient in the neonate. These data were compared to adult data from an analogous study, and suggest that the transient system is immature in infants, and that this immaturity is expressed differently by startle amplitude, probability, and latency.

Acoustic Stimulation↗
PubMed1986

The effects of age and attention upon reflex inhibition.

Previous research has suggested that reflex amplitude may be influenced by the direction of attention. The purpose of this investigation was to evaluate the effects of an attention-demanding visual reaction time task upon the elicitation of reflexes and modification of reflexes by an antecedent prestimulus in young and elderly adults. In young subjects, eyeblink inhibition was augmented by the task, yet there was no effect upon overall reflex amplitude. Elderly subjects showed no effect upon reflex inhibition while overall reflex amplitude was diminished by the task, independent of the amount of inhibition. In young subjects, the prestimulus also accentuated the initial decelerative component of a biphasic heart rate response. The reaction time task also served to augment this deceleration. The elderly heart rate response was not affected by the experimental conditions. These results provide evidence that reflex inhibition is modulated by attention. However, the relationship is complex, developmentally sensitive, and involves generalized attentive processes as well as selective attention toward specific stimuli or sensory modalities.

Adolescent↗
PubMed1985

Associative learning modifies startle reflexes at the lateral lemniscus.

Acoustic and electrical brain stimulation studies have revealed that the ventral nucleus of the lateral lemniscus is a specific site within the brain stem where a previously conditioned stimulus modulates a simple reflex, the acoustic startle response. Sixty rats were implanted with bilateral electrodes in the ventral cochlear nucleus (VCN), ventral acoustic stria (VAS), dorsal lateral lemniscus (DLL), ventral lateral lemniscus (VLL), or the nucleus reticularis pontis caudalis (RPC). Following recovery all rats were conditioned to be fearful of a light by pairing a light with a shock for 10 trials on each of 2 days. One day later, the rats were placed in cages equipped to measure startle responses. Startle was elicited either acoustically or electrically through the electrodes that had been implanted in various parts of the acoustic startle circuit. Startle was elicited in darkness or during a brief presentation of the ligh previously paired with the shock. In all groups, acoustic startle amplitude was significantly greater in the presence of the light than it was in darkness, which is consistent with previous data showing that fear increases startle. Startle elicited electrically from the VCN, VAS, and VLL was also significantly increased by the light. In contrast, startle elicited electrically in the DLL or the RPC was not affected by the light despite the fact that the same rats in the same test session had elevated acoustic startle amplitude in the presence of light. Thus, it seems that for the first time in a complex vertebrate, a locus has been found within the nervous system (the VLL) where a conditioned stimulus acts to alter neural transmission so as to affect behavior.

Acoustic Stimulation↗
PubMed1985

Evaluation of reinforcer preferences for profoundly handicapped students.

Five students classified as profoundly/multiply handicapped were trained to use microswitches to indicate reinforcer preferences. The students were trained to emit a designated motoric response (raise arm or raise head) which in turn activated a microswitch. The microswitches were connected to battery-operated toys and devices, and served to provide immediate, contingent consequences to the students for their motoric responding. The results of the investigation were evaluated within a multiple baseline (across students) with alternating treatments (potential reinforcers) design. During baseline, the students were provided with the switches and devices, but the switches were not connected to the devices. During the training conditions, the switches activated the devices. Evaluation of the devices was conducted by recording the cumulative frequency and duration of the students' responses. When the microswitches activated the devices during training, a substantial increase in the duration of motoric responding occurred for all students. In addition, some students performed differentially across devices, suggesting that they had reinforcer preferences.

Adolescent↗
PubMed1985

Teaching selected microcomputer skills to retarded students via picture prompts.

Five retarded students were taught to use picture prompts to help them access and terminate a microcomputer program. Training was provided within a multiple baseline format. Posttesting (picture prompts without feedback), and a return to baseline were later conducted for both the training program and an untrained (generalization) program. The results indicate that the program was successful in teaching the microcomputer skills to the students. In addition, all students were able to maintain their skills over a 7-day interval in which they did not have access to the microcomputer.

Adolescent↗
PubMed1985

Generalization and maintenance of complex skills by severely handicapped adolescents following picture prompt training.

Three severely handicapped adolescents were trained, using a picture prompt package, to complete three complex vocational or daily living tasks. Results indicated that all students required many training sessions to learn the first training task. Following initial training, however, all students generalized their use of the pictures across settings without additional training. The students also needed substantially reduced amounts of training on the remaining two tasks. During maintenance, two of the students continued to perform at relatively high levels of accuracy with and without the picture prompts, whereas one student continued to need the pictures.

Adolescent↗
PubMed1984

Diazepam blocks fear-enhanced startle elicited electrically from the brainstem.

Startle-like responses were elicited electrically from the ventral cochlear nucleus (VCN) in darkness or in the presence of a light that had previously been paired with shocks. These startle-like responses were potentiated by the light and potentiation was selectively decreased by diazepam in a dose-related fashion (0.625 to 2.5 mg/kg). The benzodiazepine antagonist RO15-1788 attenuated the effect of diazepam. The data indicate that potentiation of electrically elicited startle behaves like acoustically elicited startle, providing further evidence that electrical elicitation of startle is a viable experimental technique.

Animals↗
PubMed1983

Effects of picture prompts on the acquisition of complex vocational tasks by mentally retarded adolescents.

The effects of using picture prompts on the acquisition, generalization, and maintenance of complex vocational tasks were evaluated within a multiple baseline design across subjects and tasks. Five moderately and severely mentally retarded adolescents were first trained to use picture prompts to guide their performance on one or more complex tasks. Following training, posttesting with and without the picture prompts was conducted to evaluate the effects of training and to determine maintenance effects over a 2- to 4-week interval. Generalization of performance across tasks was assessed with three of the students who were provided novel tasks (with and without picture prompts) without training. Results indicated that picture prompts can be successfully used to promote both acquisition and generalization of performance, and that subsequent training time on a novel task was reduced when the use of picture prompts had been previously trained.

Adolescent↗
PubMed1983

Cardiac orienting and vowel discrimination in newborns: crucial stimulus parameters.

To delineate the acoustic parameters crucial for eliciting a cardiac deceleratory response in newborns, 2 experiments investigated stimulus dimensions implicated as important by previous research. In experiment 1, the temporal pattern and spectral complexity of moderately intense auditory stimuli influenced the cardiac responses of 24 alert newborns. Temporal pattern determined response direction: pulsed stimuli elicited cardiac deceleration, whereas continuous stimuli elicited acceleration. Stimulus complexity influenced response magnitude: the most complex stimulus, a synthetically produced vowel, produced both the largest deceleration for pulsed stimuli and the largest acceleration for continuous ones. Experiment 2 (N = 16) extended the temporal pattern effect to other vowel stimuli in a no-delay discrimination paradigm. These findings indicate that the cardiac deceleratory response to auditory stimuli is a predictable component of the newborn infant's behavior. Furthermore, they suggest that stimulus parameters that influence cardiac deceleration may also play a critical role in stimulus discrimination.

Attention↗
PubMed1979

Do 16-week-old infants anticipate stimulus offsets?

Twenty alert 16-week-old infants were presented with 20-sec tones at variable intertrial intervals for 10 trials while beat-by-beat heart rate responses were recorded to assess response at offset as well as onset of each stimulus. Consistent with past research, onsets elicited deceleratory responses which habituated and showed some evidence of dishabituation with a change in stimulus frequency on the last 2 trials. Offsets also elicited significant deceleratory responses overall, but inspection of pre-offset heart rate suggested that deceleration in anticipation of the offset event appeared after a few stimulus repetitions and increased in magnitude over trials. However, individual variability was considerable and although the anticipatory response was significant averaged over all trials, the apparent increase over trials did not reach statistical significance. The evidence clearly indicates infants quickly process and act upon temporal information in a stimulus.

Child Development↗