Effects of response‐contingent stimulus pairing on vocalizations of nonverbal children with autism

Research on stimulus–stimulus pairing to induce novel vocalizations in nonverbal children has typically employed response‐independent pairing (RIP) procedures to condition speech sounds as reinforcers. The purpose of the present study was to evaluate the effects of a response‐contingent pairing (RCP) procedure on the vocalizations of three nonverbal boys diagnosed with autism spectrum disorder. During RCP, adult‐delivered sounds that were either paired with a preferred item (target sounds) or not (nontarget sounds) were presented contingent on a button‐press response. In Experiment 1, RCP was compared with an RIP procedure, in which the timing of sound presentations was yoked to the preceding RCP session. RCP produced a greater effect on all participants' target vocalizations than RIP. Experiment 2 demonstrated the effects of differential reinforcement of the vocalizations induced in Experiment 1. The results suggest that RCP may develop vocalizations more reliably than RIP procedures.     

STIMULUS CHARACTERISTICS WITHIN DIRECTIVES: EFFECTS ON ACCURACY OF TASK COMPLETION

Three experiments were conducted in an outpatient setting with young children who had been referred for treatment of noncompliant behavior and who had coexisting receptive language or receptive vocabulary difficulties. Experiment 1 studied differential responding of the participants to a brief hierarchical directive analysis (least‐to‐most complex stimulus prompts) to identify directives that functioned as discriminative stimuli for accurate responding. Experiment 1 identified distinct patterns of accurate responding relative to manipulation of directive stimulus characteristics. Experiment 2 demonstrated that directives identified as effective or ineffective in obtaining stimulus control of accurate responding during Experiment 1 continued to control accurate responding across play activities and academic tasks. Experiment 3 probed effects of the interaction between the type of directive (effective vs. ineffective) and the reinforcement contingency (differential reinforcement for attempts vs. differential reinforcement for accurate responses) on accurate task completion and disruptive behavior. Results suggested that behavioral escalation from inaccurate responding to disruptive behavior occurred only when ineffective directives were combined with differential reinforcement for accurate task completion. The overall results are discussed in terms of developing a methodology for identifying stimulus characteristics of directives that affect accurate responding.     

AN EVALUATION OF THE RELATIONSHIP BETWEEN RECEPTIVE SPEECH SKILLS AND EXPRESSIVE SIGNING

We examined the effects of receptive speech on the acquisition of manual signing among three mentally retarded children. In an alternating treatments design, we compared the acquisition of expressive signs that were, versus were not, in a child's receptive vocabulary. The children were trained via total communication in which pictorial referents were named during sign training. Signs corresponding to known words were generally acquired faster and retained better than signs corresponding to unknown words. We conducted posttests to assess the stimulus control of signing and any changes in expressive and receptive signing and speech. Observed changes in performance could be accounted for by attention to aspects of the stimulus complex during training and functional equivalence of stimuli established by training.     

AN EVALUATION OF THE NUMBER OF PRESENTATIONS OF TARGET SOUNDS DURING STIMULUS—STIMULUS PAIRING TRIALS

We evaluated the differential effects of 2 variations of a stimulus–stimulus pairing procedure on the vocalizations of 2 children with autism. For both participants, presenting 1 sound per pairing trial resulted in a higher rate of vocalizations than 3 sounds per pairing trial.     

The effect of sonority on word segmentation: evidence for the use of a phonological universal

It has been well documented how language-specific cues may be used for word segmentation. Here, we investigate what role a language-independent phonological universal, the sonority sequencing principle (SSP), may also play. Participants were presented with an unsegmented speech stream with non-English word onsets that juxtaposed adherence to the SSP with transitional probabilities. Participants favored using the SSP in assessing word-hood, suggesting that the SSP represents a potentially powerful cue for word segmentation. To ensure the SSP influenced the segmentation process (i.e., during learning), we presented two additional groups of participants with either (a) no exposure to the stimuli prior to testing or (b) the same stimuli with pauses marking word breaks. The SSP did not influence test performance in either case, suggesting that the SSP is important for word segmentation during the learning process itself. Moreover, the fact that SSP-independent segmentation of the stimulus occurred (in the latter control condition) suggests that universals are best understood as biases rather than immutable constraints on learning.     

Infant vocal development during the first 6 months: speech quality and melodic complexity

The early development of infant non‐distress vocalizations was investigated in this study. Thirteen infants, from 4 to 24 weeks of age, and their mothers were observed weekly in a face‐to‐face interaction situation. The speech quality (syllabic versus vocalic) and melodic complexity (simple versus complex) of infant vocalizations were coded independently. Based on speech quality and melodic complexity, four types of infant non‐distress vocalizations were categorized: simple and complex syllabic (speech‐like) vocalizations as well as simple and complex vocalic (non‐speech‐like) vocalizations. Results showed that complex syllabic sounds were of longer duration and complex vocalic sounds were less frequent than the other types of vocalizations. Curvilinear developmental trends were found in the rate of simple vocalic sounds and in the mean duration of complex syllabic sounds. Furthermore, before 4 months of age, vocalic sounds were more likely to be associated with simple melodic contours, after which syllabic sounds were more likely to be associated with complex melodic contours. A dynamic systems perspective on the early development of infant vocalization is discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

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.     

Discriminative vocal conditioning in rhesus monkeys: Evidence for volitional control?

Both emotional and volitional systems are invoked in explaining the control of human vocalizations, but vocal behavior of nonhuman primates is often believed to be totally under emotional control. Monkeys' poor performance on conditioning tasks, especially discriminative conditioning of vocalization (DCV), has been cited as evidence against volitional control. In Experiment 1, rhesus monkeys failed a DCV task in which food was given for vocalizations emitted during an arbitrary visual stimulus, but in Experiment 2, monkeys showed clear discriminative performance when an otherwise comparable shock-avoidance DCV procedure was used. This evidence that monkeys possess some degree of volitional control has implications for the relation between animal vocalizations and the origin of human speech.     

Distinguishing between discriminative and motivational functions of stimuli.

A discriminative stimulus is a stimulus condition which, (1) given the momentary effectiveness of some particular type of reinforcement (2) increases the frequency of a particular type of response (3) because that stimulus condition has been correlated with an increase in the frequency with which that type of response has been followed by that type of reinforcement. Operations such as deprivation have two different effects on behavior. One is to increase the effectiveness of some object or event as reinforcement, and the other is to evoke the behavior that has in the past been followed by that object or event. "Establishing operation" is suggested as a general term for operations having these two effects. A number of situations involve what is generally assumed to be a discriminative stimulus relation, but with the third defining characteristic of the discriminative stimulus absent. Here the stimulus change functions more like an establishing operation than a discriminative stimulus, and the new term, "establishing stimulus," is suggested. There are three other possible approaches to this terminological problem, but none are entirely satisfactory.     

THE GENERALIZATION EFFECTS OF PARENT TRAINING ACROSS STIMULUS SETTINGS

Five parents of nonverbal children were trained in two home settings to modify antecedents and consequences to their children's vocalizations. Generalization effects of the parent training on both the parent's and children's behaviors under different stimulus conditions were investigated using multiple-baseline designs. Increases in parent prompting and reinforcing their children's vocalizations generalized only minimally to a new setting in the home where parent training had not occurred. Child increases in vocalizations produced by the parents in the training settings did generalize to this new setting in the home. There was minimal generalization of child vocalizations to a free-play setting at school. In a formal speech session conducted by a behavior specialist at school, only one child showed definite increases in acquisition rate as a function of the parents starting to train the sound at home.     

An evaluation of a visual–visual successive matching‐to‐sample procedure to establish equivalence classes in adults

Traditionally, behavior analysts have studied stimulus equivalence using a matching‐to‐sample (MTS) preparation. Although researchers have shown the utility of MTS to yield equivalence classes, the procedure requires several prerequisite skills for a learner to accurately respond. Previous research with humans and nonhumans has shown that relational responding can be produced via compound stimulus discrimination and successive matching‐to‐sample (S‐MTS). We conducted four experiments with college students to further evaluate the effectiveness of S‐MTS in the establishment of stimulus relations. S‐MTS trials consisted of the presentation of a single sample stimulus followed by one comparison in a fixed location on a computer screen. Depending upon the sample–comparison relation, participants touched (i.e., go) or did not touch (i.e., no‐go) the comparison stimulus. Following training of the baseline relations (AB/BC), we assessed the emergence of symmetry, transitivity, and equivalence performances (i.e., BA/CB and AC/CA). Results support the utility of the S‐MTS procedure as a possible alternative to traditional MTS. This study has direct implications for participants for whom traditional three‐array MTS procedures may be challenging.     

Competing stimulus assessments: A systematic review

The current review summarizes the literature on competing stimulus assessments (CSAs). CSAs are pretreatment assessments designed to systematically identify stimuli that reduce problem behavior (PB), ostensibly through reinforcer competition or substitution. We report on the participant characteristics, outcomes, and predictive validity of published CSAs that included (a) no-stimulus control trial(s), (b) test trials during which each stimulus was available singly and noncontingently, and (c) measurement of PB and stimulus engagement or contact. Results showed that CSAs have broad utility across a variety of topographies and functions of PB. In the majority of CSA applications for which extended analyses, or validations, were performed, stimuli shown to reduce PB during the CSA produced similar reductions during extended analysis. This was the case regardless of topography or function of PB, or whether the stimuli were assumed to be “matched” to the stimulation thought to be produced by PB. Implications for future research are discussed.     

Auditory--visual cross-modal perception of communicative stimuli in tufted capuchin monkeys (Cebus apella)

Research on cross-modal performance in nonhuman primates is limited to a small number of sensory modalities and testing methods. To broaden the scope of this research, the authors tested capuchin monkeys (Cebus apella) for a seldom-studied cross-modal capacity in nonhuman primates, auditory-visual recognition. Monkeys were simultaneously played 2 video recordings of a face producing different vocalizations and a sound recording of 1 of the vocalizations. Stimulus sets varied from naturally occurring conspecific vocalizations to experimentally controlled human speech stimuli. The authors found that monkeys preferred to view face recordings that matched presented vocal stimuli. Their preference did not differ significantly across stimulus species or other stimulus features. However, the reliability of the latter set of results may have been limited by sample size. From these results, the authors concluded that capuchin monkeys exhibit auditory-visual cross-modal perception of conspecific vocalizations.     

The Effects of Using a Conditioned Stimulus to Cue DRO Schedules

A reversal design was used to examine the effects of a differential reinforcement of other behavior (DRO) procedure and the presence of a stimulus (i.e., a bracelet), conditioned via discrimination training, on reducing socially maintained non‐contextual vocalizations in an adolescent girl with autism. Initially, a functional analysis determined that non‐contextual vocalizations were maintained by social attention. Then, discrimination training was used to establish the presence of the bracelet as a discriminative stimulus for the absence of vocalizations. Specifically, when the bracelet was on, non‐contextual vocalizations were interrupted, and edible reinforcement was provided for the absence of vocalizations. When the bracelet was off, vocalizations were not interrupted and the teacher provided social attention to the participant (i.e., reciprocated conversation with the participant about the topic). During intervention, a DRO procedure was used. The participant was presented with the bracelet, a timer set for a specified interval, and the instruction to work quietly. If vocalizations did not occur for the entire duration of the interval, the bracelet was removed and the learner was given the opportunity to engage in vocalizations. The DRO interval was systematically increased throughout the intervention. Results are discussed in terms of discrimination training as an effective addition to differential reinforcement procedure. Copyright © 2015 John Wiley & Sons, Ltd.     

Inhibitory stimulus control following errorless discrimination learning

Three generalization procedures were used to investigate inhibitory stimulus control following discrimination learning with few errors. Three groups of pigeons acquired a discrimination between a green stimulus (the positive stimulus) and a vertical or horizontal line (the negative stimulus) through differential autoshaping followed by multiple schedule presentation of the two stimuli with gradually increasing stimulus durations. Genereralization testing was along a line-tilt continuum. For one group, the test involved a resistance-to-reinforcement procedure in which responses to all line tilts were reinforced on a variable-interval schedule. For a second group, also tested with the resistance-to-reinforcement procedure, the lines were superimposed on the green field that formerly served as the positive stimulus. A third group was tested in extinction with the combined stimuli. Control groups had no discrimination training but responding to green was nondifferentially reinforced. The control subjects responded more to all line tilts during testing than did the comparable experimental subjects, indicating that the negative stimulus had become an inhibitory stimulus. Both resistance-to-reinforcement groups revealed inhibitory gradients around the negative stimulus, but the gradient for the extinction group was relatively flat. These data are consistent with others that modify Terrace's early conclusion concerning the failure of inhibition to develop during errorless training.     

Effects of stimulus eccentricity on vection reevaluated with a binocularly defined depth1

Abstract: The effects of stimulus eccentricity (central or peripheral) on vection (visually induced self‐motion perception) were investigated using a stimulus combination consisting of a static foreground and a moving background, the depths of which were defined by binocular disparity. By using these stimulus settings, the effect of stimulus eccentricity can be assessed without any artifacts in the perceived depth of the stimulus, which would covary with the stimulus eccentricity. The results of this psychophysical experiment indicated that stimulus eccentricity cannot affect the strength of vection, and that both the central and peripheral stimuli can induce self‐motion perception with equal magnitudes if the stimulus sizes are equalized. The present investigation, which used a controlled stimulus depth condition, clearly negated the idea of the peripheral dominance of vection, which has been accepted for a long time.     

The influence of correlations between noncritical features and reinforcement on stimulus generalization

One strategy to program for generalization is to vary noncritical features in teaching exemplars, thereby avoiding noncritical features from being highly correlated with reinforcement and thus gaining faulty stimulus control. In the current translational evaluation, 2 groups of adults of typical development were taught to respond to arbitrary stimuli with experimenter‐defined critical and noncritical features in a matching‐to‐sample task. The teaching arrangement used for 1 group programmed for low correlation between noncritical features and reinforcement; the teaching arrangement used for the other group programmed for high correlation between noncritical features and reinforcement. Participants in the former group displayed (a) faster acquisition of matching, (b) less variability in correct responding, and (c) a decreased likelihood of faulty stimulus control developing during training. The results contribute towards advancing the study of stimulus control and developing an explicit technology of generalization to better serve consumers of the application of our science.     

Establishing derived categorical responding in children with disabilities using the PEAK‐E curriculum

The purpose of the study was to evaluate a procedure to generate derived categorical responding by three children with disabilities and to promote the emergence of untrained intraverbal categorical responses. In the study, three 4‐member equivalence classes including three stimuli (A, B, and C) and a category name (D) for each class were trained using a match‐to‐sample procedure. Test probes were conducted for categorical responding, including both a trained (D‐A) and two derived (D‐B, D‐C) relational responses, as well as the emergence of untrained intraverbal categorical responding (D‐A/B/C) throughout the study. Relational training was effective at promoting the emergence of categorical responding, and two of the three participants demonstrated the emergence of additional intraverbal responding without prior training. The results provide further evidence supporting the practical utility of stimulus equivalence as well as the PEAK‐E curriculum.     

IDENTIFYING REINFORCERS FOR PERSONS WITH PROFOUND HANDICAPS: STAFF OPINION VERSUS SYSTEMATIC ASSESSMENT OF PREFERENCES

We evaluated a systematic means of determining stimulus preferences among seven profoundly handicapped persons. Preferences were determined by observing student approach responses to individual stimuli. Results indicated that there were differential stimulus preferences across the multiply handicapped participants. However, results of the systematic assessment did not coincide with the results of a more traditional, caregiver-opinion method of assessing student preferences. A second experiment was then conducted with five participants to evaluate whether stimuli that were assessed to consistently represent preferences would function as reinforcers in skill training programs. Results indicated that stimuli that were systematically assessed to represent student preferences typically functioned as reinforcers when applied contingently. However, preferred stimuli as reflected by caregiver opinion did not function as reinforcers unless those stimuli were also preferred on the systematic assessment. Results are discussed in terms of assisting profoundly handicapped persons by (a) improving the effectiveness of training programs by increasing the likelihood of using stimuli that have reinforcing value and (b) increasing the overall quality of life by providing preferred stimuli in the routine living environment.