The blocking effect of pictorial prompts on sight-word reading

This study replicates and extends previous work showing that pictorial prompts can interfere with the learning of sight words by students with moderate mental retardation. Effects of training with 6 students were assessed during five conditions using an alternating treatments design. In four conditions, words were presented either alone or with a corresponding picture. In a fifth condition, pictures were used to provide feedback. The results showed that acquisition was achieved fastest during the word-alone conditions with 5 students.     

Analysis of response repetition as an error-correction strategy during sight-word reading

A great deal is known about the effects of positive reinforcement on response acquisition; by contrast, much less research has been conducted on contingencies applied to errors. We examined the effects of response repetition as an error-correction procedure on the sight-word reading performance of 11 adults with developmental disabilities. Study 1 compared single-response (SR) repetition and multiple-response (MR) repetition, and results showed that all 6 participants acquired more sight words with the MR procedure. Study 2 compared MR error correction following every incorrect response (continuous) and following one third of incorrect responses (intermittent), and results showed that all 6 participants acquired more sight words when error correction was continuous. Study 3 compared MR error correction in which errors required practice of the training word (relevant) versus a different word (irrelevant), and results showed that 3 of 9 participants showed better performance under the relevant condition; however, all participants showed improvement even under the irrelevant condition. Findings are discussed in terms of the behavioral processes by which error correction may enhance performance during acquisition.     

A comparison of prompting methods to teach sight words to students with autism spectrum disorder

Time delay procedures are one of the most commonly used and effective strategies for teaching sight words to learners with disabilities. However, less is known about whether they are differentially effective and efficient with learners. This study compared the effectiveness and efficiency of progressive time delay and simultaneous prompting on sight word acquisition among three learners with autism spectrum disorder using an adapted alternating treatments design across word sets. For two participants, both procedures led to skill acquisition with no clear differences in efficiency. For the remaining participant, neither procedure was effective; therefore, the reading task was changed to a receptive one, and a stimulus fading intervention package was implemented.     

A comparison of methods for teaching receptive labeling to children with autism spectrum disorders

Many early intervention curricular manuals recommend teaching auditory-visual conditional discriminations (i.e., receptive labeling) using the simple-conditional method in which component simple discriminations are taught in isolation and in the presence of a distracter stimulus before the learner is required to respond conditionally. Some have argued that this procedure might be susceptible to faulty stimulus control such as stimulus overselectivity (Green, 2001). Consequently, there has been a call for the use of alternative teaching procedures such as the conditional-only method, which involves conditional discrimination training from the onset of intervention. The purpose of the present study was to compare the simple-conditional and conditional-only methods for teaching receptive labeling to 3 young children diagnosed with autism spectrum disorders. The data indicated that the conditional-only method was a more reliable and efficient teaching procedure. In addition, several error patterns emerged during training using the simple-conditional method. The implications of the results with respect to current teaching practices in early intervention programs are discussed.     

EFFECTS OF WITHIN-STIMULUS AND EXTRA-STIMULUS PROMPTING ON DISCRIMINATION LEARNING IN AUTISTIC CHILDREN1

Two different prompting procedures to teach visual and auditory discriminations to autistic children were compared. The first involved presenting an added cue as an extra-stimulus prompt. This required the child to respond to both prompt and training stimulus. The second involved the use of a within-stimulus prompt. This consisted of an exaggeration of the relevant component of the training stimulus and thus did not require that the child respond to multiple cues. The results indicated that (1) children usually failed to learn the discriminations without a prompt, (2) children always failed to learn when the extra-stimulus prompt was employed but usually did learn with the withinstimulus prompt, and (3) these findings were independent of which modality (auditory or visual) was required for the discrimination.     

Short-term remembering of discriminative stimuli in pigeons.

Pigeons learned to peck the left or right of two white keys depending on whether a red or a green stimulus was displayed on a third key. The opportunity to peck the white keys was then dealyed for zero to six seconds after the red or green (to-be-remembered) stimulus. On half the trials, the feeder operated during the delay to interrupt behavior that might mediate discriminated responding. No events were scheduled on the remaining trials. In a later condition, the pigeons had the opportunity to peck the white keys during the delay. In general, accuracy decreased as delay increased in all conditions, but performance was least accurate following feeder operations and most accurate when pecking was allowed during the delay. The procedures may be analogous to varying the opportunity for rehearsal in studies of human short-term memory.     

Use of a differential observing response to expand restricted stimulus control

This study extends previous work on the use of differential observing responses (DOR) to remediate atypically restricted stimulus control. A participant with autism had high matching-to-sample accuracy scores with printed words that had no letters in common (e.g., cat, lid, bug) but poor accuracy with words that had two letters in common (e.g., cat, can, car). In the DOR intervention, she matched the distinguishing letters of the overlapping words (e.g., t, n, r) immediately prior to matching the whole words. Accuracy scores improved, and accuracy remained high when DOR requirements were withdrawn.     

Disruptive effects of stimulus intensity on two variations of a temporal discrimination procedure

Previous reports using stimulus intensity changes to disrupt temporal discrimination have shown shifts in the psychophysical curve for time, while studies using other disruptors have shown a flattening of the curve. The current study investigated the impact of increases and decreases in stimulus intensity on temporal discrimination in pigeons, to determine if a flattening of the curve could be extended to this disruptor. The brightness of the sample to be timed was manipulated under two procedural variations, in which the response alternatives were differentiated by color or location. Results showed that all subjects in the color procedure, and one in the location procedure, showed a flattening of the psychophysical curve when they experienced increased stimulus intensity in descending order. No subjects exposed to an ascending order of stimulus intensities, and none of the other subjects in the location procedure, showed any impact of changed stimulus intensity. Minimal disruption was found when test sessions presented decreased stimulus intensity levels in a second series. These results, together with those using other types of disruptors, add to the evidence of a flattening of the psychophysical curve when temporal discrimination is disrupted.     

A note on the measurement of conditional discrimination.

An analysis of some extreme forms of stimulus control that a simple conditional-discrimination procedure can generate leads to the conclusion that accuracy does not provide an orderly scale of measurement. Dependence on accuracy to evaluate a conditional discrimination, particularly at intermediate levels of accuracy, can generate erroneous conclusions about the extent to which the controlling relations are those specified by the experimenter.     

Quantitative and methodological aspects of stimulus equivalence

The number of different ways of linking stimuli in the training phase of a conditional discrimination procedure designed to teach equivalence relations has hitherto been underestimated. An algorithm from graph theory that produces the correct number of such different ways is given. The establishment of equivalence relations requires transitive stimulus control. A misconception in a previous analysis of the conditions necessary for demonstrating transitive stimulus control is indicated. This misconception concerns responding in an unreinforced test trial to a negative rather than a positive comparison stimulus. Such behavior cannot be attributed to discriminative control by degree of association with reinforcement if the negative comparison stimulus has been less associated with reinforcement than the positive comparison stimulus in an antecedent training phase.     

Memory for two stimulus-response items in pigeons

Six pigeons served in a discrete-trial experiment on short-term memory. Combinations of three key positions and two ordinal positions, yielding six possible sequences of stimulus-response pairs, were used as lists of items. A retention interval separated list presentation from the test phase in which two (for Group 1) or three (for Group 2) keys were illuminated with either red or green light. A reinforcer was delivered if a subject pecked the key of the first item on a red trial and the key of the second item on a green trial. When the retention interval was lengthened from one to five or nine seconds, a systematic loss of stimulus control resulted. Lengthening the interval between items from one to eight seconds had a much smaller effect for the birds in Group 1, whereas a systematic loss of stimulus control was found in red trials for the birds in Group 2. The functional relations between choice accuracy and delay provided an empirical basis for analysis of what relations among temporal events can become discriminative stimuli.     

Comparison of two discrimination methods in teaching Chinese children with autism

In teaching conditional discriminations to children with autism spectrum disorder (ASD), practitioners may progress from simple to conditional discriminations or may teach conditional discriminations from the onset of instruction. Some research indicates that teaching simple discriminations first may be unnecessary and that teaching may more efficiently focus on conditional discriminations exclusively. This study replicated comparisons of simple-to-conditional and conditional-only discrimination training methods in teaching audio-visual conditional discriminations to Chinese preschoolers with ASD. Results indicated the conditional-only training method appeared to be more efficient in teaching these skills.     

Adventitious control by the location of comparison stimuli in conditional discriminations.

In a conditional discrimination procedure, samples appeared in a center key, and comparisons appeared in two of four outer keys. The location of comparison keys varied from trial to trial. Separate learning curves for each of the six possible pairs of comparison keys were plotted in a signal-detection space, revealing different patterns of progress on each pair. Also, when learned conditional discriminations were disrupted, pairs of keys differed in their patterns of disruption. Varying the location of comparison stimuli among six different pairs of keys had not eliminated key position as a controlling aspect of the stimuli. The variations simply increased the number of stimulus compounds--key position and experimental stimuli--that the subject learned. Plotting conditional-discrimination learning curves in a signal-detection space reveals relations among hits, false alarms, accuracy, and comparison preference that help to define a subject's progress.     

Construction of equal-hue discriminability scales for the pigeon.

Equal-hue discriminability steps for the pigeon are shown as tabular entries that can be summed or interpolated to produce sequences of equal discriminability steps of various step size. Equal-hue discriminability sequences can be constructed where the number of stimuli and spectral range are specified, or where an interval in one spectral region is to be equated to an interval in another spectral region.     

Multiple schedules in practical application: Research trends and implications for future investigation

Researchers began studying multiple schedules in basic laboratories, but recent advances have extended research on multiple schedules to a wide variety of socially significant applications, especially during the last decade. Applied researchers have used multiple schedules to (a) promote stimulus control over high‐rate appropriate behaviors, (b) thin the schedule of reinforcement following functional communication training, and (c) obtain stimulus control over problem behaviors maintained by automatic reinforcement. In the current paper, we reviewed 31 studies with 147 applications identified through a search of the applied literature on multiple schedules. Using these studies, we (a) reviewed the empirical literature on multiple schedules, (b) recommended multiple‐schedule procedures that serve as best practice guidelines for applied behavior analysts, (c) identified the generality and boundaries of current knowledge about the effectiveness of multiple schedules, and (d) critically analyzed the literature to provide directions for future multiple‐schedule research.     

Comparison of naturalistic and arbitrary discriminative stimuli during schedule thinning following functional communication training

We replicated and extended research on incorporating naturalistic discriminative stimuli into schedule thinning following functional communication training with three boys with autism spectrum disorder who engaged in severe behavior. Comparing naturalistic to arbitrary discriminative stimuli, two participants demonstrated differentiated communication in fewer sessions when arbitrary stimuli were used, while the third participant mastered the discriminations in a comparable number of sessions. Although previous research has demonstrated success in rapidly thinning the schedule with arbitrary stimuli, we extended this line of research by evaluating the extent to which differentiated communication would maintain during rapid schedule thinning in both naturalistic and arbitrary conditions. Two participants' communication remained differentiated, and in both conditions, during rapid schedule thinning. However, neither discrimination maintained for the third participant. Results are discussed in terms of the existing literature and directions for future research.     

Stimulus control and generalization of point-loss punishment with humans

Two experiments demonstrated stimulus control and generalization of conditioned punishment with humans. In both studies, responses first were reinforced with points exchangeable for money on a variable-interval schedule in the presence of one line length (S(D)). Next, a second line length was introduced, and point loss followed every response in the presence of that line (S(D)p). In the final training condition, points were deducted at session end. Response rate was lower in the presence of the S(D)p despite equal rates of points for money in the presence of both stimuli. In generalization testing for Experiment 1, the two lines were included in a 10-line continuum; S(D)p fell in the middle and the trained SD was at one end. Lines were presented randomly, and point delivery and loss contingencies were as in training but with points available in the presence of all lines. For all subjects, response rates were lowest around S(D)p and increased towards the SD end of the continuum. Because testing included only one or two lines beyond S(D), this pattern did not rule out S(D) generalization. Thus, in Experiment 2, stimuli beyond S(D) were added to generalization tests. Response rates did not decrease as a function of distance from S(D), clarifying the demonstration of punishment generalization.