An example of discovery research involving the transfer of stimulus control

The initial purpose of the present study was to replicate procedures for teaching preschool children to recruit attention at appropriate times by having an experimenter signal the availability and unavailability of attention (i.e., arrange a multiple schedule involving reinforcement and extinction; Tiger & Hanley, 2004). Following the development of discriminated social responding, the schedule-correlated stimuli were removed (i.e., a mixed schedule of reinforcement was arranged). However, discriminated responding continued during these conditions. Further evaluation suggested that stimulus control over children's social responding had transferred from the schedule-correlated stimuli to the delivery of reinforcement. The effect of a history of reinforcement under multiple-schedule conditions on performance under mixed schedules was then replicated with 2 participants in a reversal design. These findings suggest that following experience with schedule-correlated stimuli, these stimuli may be removed with only modest disruption to discriminated responding.     

Developing stimulus control of young children's requests to teachers: classwide applications of multiple schedules

Children may recruit their teachers' attention at undesirably high rates or at inconvenient times. Tiger and Hanley (2004) described a multiple-schedule procedure to reduce ill-timed requests, which involved providing children with two distinct continuous signals that were correlated with periods in which teacher attention was either available or unavailable. The current study extended the application of multiple schedules by evaluating the effectiveness of the procedure when implemented by private-school teachers in 3 elementary classrooms. Following the introduction of the multiple schedules, student approaches toward their teacher were maintained during desirable periods but were minimized during undesirable periods.     

Assessing the value of choice in a token system

Responding of 4 children was assessed under conditions in which (a) no programmed contingencies were arranged for target behavior, (b) responding produced tokens that could be exchanged for a single highly preferred edible item, and (c) responding produced a token that could be exchanged for a variety of preferred edible items. After assessing the effects of these contingencies, the preferences of 3 participants were assessed using a concurrent-chains schedule. Preference for the opportunity to choose from the same or qualitatively different edible items varied across participants, and findings were generally consistent with those of Tiger, Hanley, and Hernandez (2006).     

An evaluation of multiple‐schedule variations to reduce high‐rate requests in the picture exchange communication system

Using procedures similar to those of Tiger, Hanley, and Heal (2006), we compared two multiple‐schedule variations (S+/S– and S+ only) to treat high‐rate requests for edible items in the Picture Exchange Communication System (PECS). Two individuals with autism participated, after they showed persistent requests for edible items after PECS training. Stimulus control was achieved only with the multiple schedule that involved presentation of a discriminative stimulus during reinforcement components and its removal during extinction components (S+ only). Discriminated requests were maintained for the 1 participant who experienced schedule thinning.     

Discriminated functional communication: a procedural extension of functional communication training

A limitation associated with communication-based interventions for problem behavior is the potential for requesting reinforcement at high rates. Multiple-schedule arrangements have been demonstrated to be effective for controlling rates of responding (Hanley, Iwata, & Thompson, 2001). In the current study, we extended previous research by teaching individuals to attend to naturally occurring discriminative stimuli (e.g., caregiver behavior) instead of arbitrary stimuli (e.g., picture cards). Following successful treatment with functional communication and extinction, 2 participants were taught to request attention differentially based on whether the caregiver was engaging in a variety of "busy" (e.g., talking on the phone) or "nonbusy" (e.g., reading a magazine) activities. Following training, each participant engaged in communication primarily when caregivers were engaged in nonbusy activities.     

Conditioned reinforcement and discrimination in second-order schedules

Pigeons were exposed to multiple second-order schedules in which responding on the “main key” was reinforced according to either a variable-interval or fixed-interval schedule by production of a brief stimulus on the “brief-stimulus key”. A response was required to the brief stimulus during its fourth (final) presentation to produce food; responses to the earlier brief stimuli indicated the extent to which the final brief stimulus was discriminated from preceding ones. Main-key response rates were higher in early components of paired brief-stimulus schedules, in which each brief stimulus was the same as that paired with reinforcement, than in comparable unpaired brief-stimulus or tandem schedules. Poor discrimination occurred between paired brief stimuli (Experiment I). When chain stimuli on the main key induced a discrimination between the first two and second two brief stimuli, the response-rate enhancement in the paired brief-stimulus schedule persisted (Experiment II). Rate enhancement diminished when the initial link of the chain included the first three components (Experiment IV). Eliminating the contingency between responding and brief-stimulus production also diminished rate enhancement (Experiment III). The results show that the discriminative and conditioned reinforcing effects of food-paired brief stimuli may be selectively manipulated and suggest that the reinforcing effects are modulated by other reinforcers in the situation.     

Control of echolalic speech in psychotic children

Immediate echolalia, a common language disorder in psychotic children, was studied in a series of replicated single-subject designs across six schizophrenic and five normal children. In Experiment 1, each child was presented with several questions and commands, some of which set the occasion for specific, appropriate responses and some of which did not. The former were referred to as discriminative stimuli and the latter, as neutral stimuli. The psychotic children tended to echo the neutral stimuli while responding appropriately to the discriminative stimuli; the normal children, in contrast, typically echoed neither type of stimulus. In Experiment 2, three psychotic children were taught appropriate responses to each of several neutral stimuli. Following this training, the children generally responded appropriately to these stimuli without echoing. A plausible interpretation of these results is that the neutral stimuli were initially incomprehensible or meaningless to the children (whereas the discriminative stimuli were comprehensible or meaningful) and that verbal incomprehensibility may be one important determinant of immediate echolalia. Finally, the results are noteworthy in that they isolate a sufficient treatment variable (i.e., the reinforcement of alternative, nonecholalic responses) for eliminating instances of this language anomaly.     

It is more difficult to retrieve a familiar person's name and occupation from their voice than from their blurred face

Damjanovic and Hanley (2007) showed that episodic information is more readily retrieved from familiar faces than familiar voices, even when the two presentation modalities are matched for overall recognition rates by blurring the faces. This pattern of performance contrasts with the results obtained by Hanley and Turner (2000) who showed that semantic information could be recalled equally easily from familiar blurred faces and voices. The current study used the procedure developed by Hanley and Turner (2000) and applied it to the stimuli used by Damjanovic and Hanley (2007). The findings showed a marked decrease in retrieval of occupations and names from familiar voices relative to blurred faces even though the two modalities were matched for overall levels of recognition and rated familiarity. Similar results were obtained in Experiment 2 in which the same participants were asked to recognise both faces and voices. It is argued that these findings pose problems for any model of person recognition (e.g., Burton, Bruce, & Johnston, 1990) in which familiarity decisions occur beyond the point at which information from different modalities has been integrated.     

Separating the reinforcing and discriminative properties of brief-stimulus presentations in second-order schedules.

Pigeons' responses were maintained under multiple schedules to study properties of briefly presented stimuli. Responses in one component produced food according to a second-order schedule with fixed-interval components in which food or a brief stimulus occurred with equal probability. In the second component responses produced only the brief stimulus under a fixed-ratio schedule. Under various conditions the brief stimulus in the first component was (a) paired with food, (b) not paired with food, (c) partially omitted, or (d) scheduled simultaneously with the second-order schedule under an independent variable-interval schedule. Paired and nonpaired brief stimuli maintained similar response patterning in the second-order schedule. However, only paired stimuli maintained responses in the second component. The data suggest that nonpaired brief stimuli engender response patterning in second-order schedules as a result of their discriminative properties. When the stimulus is paired with food, these discriminative properties sometime mask a reinforcement effect, and no change in response patterning is observed. When the discriminative properties of the brief stimulus are absent, the reinforcing effects of pairing the brief stimulus with food may be observed.     

Assessing the generality and durability of interview‐informed functional analyses and treatment

Due to the limited research demonstrating socially valid outcomes of function‐based treatments in ecologically relevant environments (Santiago, Hanley, Moore, & Jin, 2016), we replicated and extended the effects of the interview‐informed functional analysis and skill‐based treatment procedure described by Hanley, Jin, Vanselow, and Hanratty (2014) with two children diagnosed with autism in a home setting. The assessment and treatment was implemented by a home‐based service provider and treatment was extended to the participants’ parents. Following the interview‐informed functional analyses, we taught the participants functional communication responses and to engage in less‐preferred activities when functional communication outcomes were delayed. We observed large reductions in problem behavior following the introduction of the function‐based treatment. The effects extended to novel settings, stimuli, and caregivers and the results maintained at 6‐week follow‐ups.     

Preschool life skills: Recent advancements and future directions

Over the past decade, researchers have replicated and extended research on the preschool life skills (PLS) program developed by Hanley, Heal, Tiger, and Ingvarsson (2007). This review summarizes recent research with respect to maximizing skill acquisition, improving generality, evaluating feasibility and acceptability, and testing predictions of the initial PLS study. For each area, we suggest directions for future research.     

Emergent simple discrimination in children: Preference for non-preferred stimuli

Previous research (Smeets, 1991) suggested that when given a new discrimination, children respond on the basis of physical similarity with previously discriminated stimuli. They respond to a stimulus similar to another preferred stimulus (S+ transfer) and respond away from a stimulus similar to another nonpreferred stimulus (S- transfer). When both types of transfer apply to the same stimulus, S+ transfer prevails, S+ Priority Transfer (S+PT). The present study demonstrated that S+PT also occurs when the criterion task consists of two nonpreferred stimuli. When given a choice between two previously nonpreferred stimuli, one similar and one dissimilar to other preferred stimuli, children select the first one. They do not so, however, when a nonpreferred stimulus resembling another preferred stimulus is presented with a new nonpreferred stimulus. These findings suggest that the children's preferences were not based on the physical resemblance with other (non)preferred stimuli but on the functions (S+, S-, S0) of individual stimulus components. A theoretical model is presented that accounts for all experimental data reported in the previous and present study. The model implies that discriminative responding not only results from but also determines the functional properties of individual stimulus elements.     

Differential production of positive and negative discriminative stimuli by normal and retarded children

Using an observing procedure similar to Wyckoff's (1969), two normal and two mentally retarded children were studied. The children were initially trained to earn pennies by pressing a rectangular key according to a multiple variable-interval extinction schedule of reinforcement. After discrimination training, the children were allowed to produce the discriminative stimuli by depressing a second or observing key. The retarded children were different from the normal children in that they produced more of the positive discriminative stimulus (S+) than the negative discriminative stimulus (S?). In the case of the retarded children, S+ observing started high and remained high. In the case of the normal children, S+ observing was initially substantial and then rapidly diminished.     

Schedules using noxious stimuli. II: low intensity electric shock as a discriminative stimulus

The presence or absence of pulses of low intensity electric shock was used as a discriminative stimulus to control responding under fixed ratio reinforcement in the squirrel monkey. Initially brief periods of nonreinforcement were lengthened only when discriminative control was evident. Discriminative control was studied by (1) varying the duration of nonreinforcement periods; (2) reversing the stimulus conditions correlated with reinforcement and nonreinforcement periods; and (3) determining the minimum shock intensity necessary to maintain discriminative control. Stimulus control was not reliably affected by d-amphetamine, chlorpromazine, or morphine. The discriminative control by pulses of low intensity electric shock was similar to that by other discriminative stimuli, except that the control developed slowly and was better when the pulsing shock was correlated with reinforcement than when correlated with nonreinforcement.     

A New Look at Gaze: Preschool Children's Understanding of Eye-Direction

This study challenges the consensus view that children can judge what someone is looking at from infancy. In the first experiment 2-, 3-, and 4-year-old children were asked to judge what a person in a drawing was looking at and which of two people was “looking at” them. Only 6% of 2-year-olds and young 3-year-olds passed both gaze-direction tasks, but over 70% passed an analogous point-direction task. Most older 3-year-olds and 4-year-olds passed all three tasks. Experiment 2 compared children's ability to judge what the experimenter was looking at with performance on the picture tasks. Three-year-olds performed significantly worse than 4-year-olds on the real life and picture gaze tasks. Performances on the two types of gaze task were highly correlated. Experiment 3 included stimuli with the additional cue of head-direction. Even the younger children performed well on these stimuli. These results suggest that, regardless of task format, children cannot judge what someone is looking at from eye-direction alone until the age of 3 years. Weaknesses in the evidence supporting the consensus view are highlighted and discussed.     

The effectiveness of and preschoolers' preferences for variations of multiple-schedule arrangements

Multiple schedules of reinforcement have been used to teach children to recruit attention only when it is available, thereby minimizing disruptive requesting during instructional activities. This procedure involves alternating periods of continuous reinforcement (CRF) with periods of extinction and correlating each period with a distinct and continuous discriminative stimulus. The present study evaluated the effectiveness of and children's preferences for multiple schedules in which (a) two different stimuli, one correlated with reinforcement (S+) and another correlated with extinction (S-), were presented; (b) only an S+ was presented (i.e., no stimulus was correlated with extinction), and (c) neither an S+ nor an S- was presented (i.e., a mixed schedule). S+/S- and S+ arrangements were similarly effective for 7 children, but 3 preferred the S+/S- condition and 4 preferred the S+ condition. Correlational analyses suggested that children who responded more effectively given the S- (discrimination indexes were relatively high) preferred the S+/S- condition, whereas children who responded less effectively given the S- preferred the S+ condition. The implications of these findings for arranging multiple schedules for social responses are discussed.     

Evidence for a non-lexical influence on children's auditory repetition of familiar words

This paper examines evidence for a nonlexical influence on children's repetition of real words. We investigate the extent to which two computational models of auditory repetition can simulate the performance of 68 children aged between 5 and 11?years-old when they are attempting to repeat familiar words. Both computational accounts were derived from Foygel and Dell's (J Mem Lang 43:182-216, 2000) semantic-phonological model of picture-naming. Results showed that a dual-route model in which a lexical and a nonlexical route work together to repeat familiar words (Hanley et?al. in Cogn Neuropsychol 21:147-158, 2004) provided an accurate simulation of children's repetition, whereas Foygel and Dell (J Mem Lang 43:182-216, 2000) single lexical-route model under-predicted performance. The only exception was the repetition performance of 5?year-old children, which was over-predicted by the dual-route model. It is argued that at 5?years of age, some children have available both a lexical and a nonlexical repetition route but the output of the two routes does not summate when real words are being repeated. Some young children may lack the attentional skills that would enable them to co-ordinate the activity of the lexical and nonlexical repetition routes.     

A DISCRIMINATION TRAINING PROCEDURE TO ESTABLISH CONDITIONED REINFORCERS FOR CHILDREN WITH AUTISM

Although conditioned reinforcers are used in many behavioral intervention programs for individuals with developmental disabilities, little research has been conducted to determine optimal methods for establishing conditioned reinforcers. An early method that has received relatively little research attention is to condition a neutral stimulus as a discriminative stimulus and then use the stimulus as a programed consequence during skill acquisition. The current study evaluated the effects of a discrimination training procedure on establishing conditioned reinforcers for three children with autism. For all participants, previously neutral stimuli reinforced behaviors after acquiring discriminative properties during discrimination training. Copyright © 2014 John Wiley & Sons, Ltd.     

Discriminative properties of briefly presented stimuli

In Experiment I, pigeons' responses produced food according to a fixed-interval schedule while responses on the key also produced brief stimuli according to a variable-interval schedule. Each brief stimulus reset the fixed interval. Thus, a brief stimulus occurred irregularly but a fixed minimum time separated the occurrence of food from a brief stimulus. Pauses followed brief stimuli and were followed by an accelerated response rate until another brief stimulus or food occurred. In Experiment II, four control procedures were examined. (1) Brief-stimulus presentations were omitted, producing a loss of response patterning. (2) A second-order schedule was studied with fixed-interval components. This schedule produced patterning following brief stimuli similar in kind and degree to that found in Experiment I. (3) A conjoint schedule was arranged in which food was no longer separated from the stimulus by a fixed time; pauses following the stimulus no longer resulted. (4) A brief food reinforcer replaced the brief visual stimulus, resulting in a constant response rate with no pausing following the brief food stimulus. The results suggest that the brief-stimulus effects were due to discriminative functions produced by the fixed temporal relation separating the stimulus from food.     

Second-order schedules: a comparison of chained, brief-stimulus, and tandem procedures

Pigeons were exposed to seven types of two-component schedules, each component a 2-min fixed-interval schedule. Food presentation occurred at the completion of the second component under all conditions. The seven types of schedules were: (1) a chained schedule in which completion of the first component produced the discriminative stimulus associated with the second component; (2) a chained schedule to which was added the brief presentation of a food-paired stimulus at the completion of the first component; (3) a chained schedule to which was added the brief presentation of a stimulus not paired with food at the completion of the first component; (4) a multiple schedule in which food presentation occurred at the completion of both components; (5) a tandem schedule in which completion of the first component initiated the second component, with no changes in exteroceptive stimuli; (6) a food-paired brief-stimulus schedule in which the brief presentation of a food-paired stimulus was made at the completion of the first component and no other changes in stimuli occurred; and (7) a brief-stimulus schedule in which the brief presentation of a stimulus not paired with food was made at the completion of the first component and no other changes in stimuli occurred. Positively accelerated patterns of responding developed in the first component under three conditions: (1) the chained schedule with the added food-paired brief stimulus; (2) the multiple schedule; and (3) the food-paired brief-stimulus schedule. Response rates were low in the first component, with few instances of positively accelerated patterns, under two conditions: (1) the chained schedule; and (2) the chained schedule with the added nonpaired brief stimulus. The results suggest that a briefly presented food-paired stimulus may function as a more effective conditioned reinforcer than does the presentation of a discriminative stimulus.