Development Of Stimulus Control Research Articles

A Review of Prompt-Fading Procedures, Part II: Parameters and Components

Instructors use prompts to assist learners in acquiring skills and then fade those prompts until responding occurs under the appropriate stimulus control conditions. Cengher et al. Journal of Developmental and Physical Disabilities, 30, 155-173 (2018) reviewed studies that compared two or more different prompt-fading procedures. The current review extends the literature by analyzing studies that manipulated parameters and components of prompt-fading procedures. The data search and data analysis processes were similar to the ones reported by Cengher et al. Journal of Developmental and Physical Disabilities, 30, 155-173 (2018). The results support the selection of self-paced, individualized instruction that programs the appropriate development of stimulus control by fading within the discriminative stimulus, using an observing response, and teaching a conditional discrimination from the onset of training. Even though the results were generally consistent across studies, there are some parameters and components that have more empirical support and others that require continued investigation. Implications for clinical practice and directions for future research are discussed.

Attention and psychophysics in the development of stimulus control

Rats responded in a six-stimulus, two-response temporal classification procedure. A successive-reversal design was used in which the relationship between stimulus class (short vs. long) and correct comparison location (left or right) reversed every 15 sessions. After several reversals, the relative probability of reinforcement for each correct classification was manipulated across subsequent reversals. In each condition, the asymptotic level of preference for the comparison location (response bias) correlated with the greater probability of reinforcement was demonstrated in the first session following a reversal, whereas discrimination accuracy took several more sessions to return to asymptotic levels. A modified version of the attending-augmented Davison-Nevin-Alsop (Davison & Nevin, 1999) model offered by Nevin, Davison, & Shahan (2005) provided an accurate description of the reacquisition data. The comparison-attending parameters remained high and relatively constant following reversals, while sample-attending parameters initially decreased following reversals, and then increased gradually across sessions. These findings support key assumptions of the attending model; sample- and comparison-attending are independent processes that modulate the expression of discriminative control exerted by those stimuli over operant behavior.

The development of stimulus control over tics: A potential explanation for contextually-based variability in the symptoms of Tourette syndrome

Research has demonstrated that providing reinforcement for tic-free intervals can decrease tic frequency in controlled analogue settings. The aim of the current study was to determine whether reinforcement could be used to create stimulus control over tic expression. Ten children with chronic tic disorders (including Tourette syndrome) completed four discrimination training sessions. Each session consisted of three exposures to each of three, 5min conditions presented in a random order. In one condition, participants were reinforced for tic absence on a 10-s fixed interval schedule in the presence of a purple light. In a second condition, participants were instructed to suppress their tics, but were not reinforced for doing so in the presence of an orange light. In a third condition, participants were instructed not to suppress their tics in the presence of two non-illuminated lights. Confirming findings from other studies, results showed that reinforcing tic suppression reduced tic frequency to a greater extent than only providing instructions to suppress. To test for stimulus control, a fifth session was conducted following the aforementioned discrimination training sessions. The fifth session consisted of three exposures to each of three 5min conditions presented in a random order. In one condition, a purple light was illuminated. In a second condition, an orange light was illuminated. In a third condition, neither light was illuminated. Across all three conditions, instructions to suppress (or not suppress) tics were not provided, and reinforcers for successful suppression were not delivered. Results indicated that in the presence of the purple light, tics were significantly lower than when neither light was illuminated. These findings provide preliminary support for the idea that a history of differential reinforcement in various contexts may play a role explaining variability in tic symptom expression.

A review of the behavioral theories of autism and evidence for an environmental etiology.

Abstract The behavior analytic theories of autism are reviewed and evidence related to the theo ries and environmental causes of autism are discussed. There is little evidence that autism is caused by deviant parenting practices. However, changing parenting practices can lead to improvements in child behavior, and functional analyses have shown that the behaviors of children with autism can be explained and treated using the principles of behavior analysis. The research lends some support for two theories. The first is that autism consists of a mismatch between the child’s nervous system and the envir onment. The second is that children with autism have a special difficulty in the development of stimulus control and that is especially pronounced in the area of social behavior because the contingencies are less reliable in the social world relative to th e nonsocial. Keyw ords : etiology, behavior analytic theories, autism Introduction Autism, Asperger’s Syndrome, and pervasive developmental disorder -not otherwise specified (PDD -NOS ) represent the Autism Spectrum Disorders (ASD s). Currently considered a low -incidence disability, autism is the fastest growing developmental disability (Autism Society of America, 2003). The average age of diagnosis is 3 -4 years of age (Filipek et al., 1999), however some studies suggest diagno sis is possible as early as 15 months (Klin et al., 2004), others suggest 18 to 24 months (Eaves & Ho, 2004). The importance of early identification is tied to providing intervention services. The earlier intervention services are provided, the better the outcome. Lovaas (1987, 1993) demonstrated the effectiveness of early intervention for children with autism. More recently, Harris and Handleman (2000) indicated age at which intervention is provided is a predictor of later outcome, with children younger th an 48 months benefiting from intervention more than older children. Autism includes impairment across several areas of functioning, however general descriptions will not describe all individuals with autism perfectly, as severity and symptoms are idiosy ncratic. Often referred to as the “triad problems,” the essential features of autism include impaired communication (verbal and gestural), social functioning, and behavioral variability (i.e., restricted and repetitive activities) that appear in the first 36 months of life (American Psychiatric Association, 2000; Wetherby et al., 2004). Other problems associated with autism include sensory and perceptual deficits, behavior problems, and intellectual disability (American Psychiatric Association, 2000; Carpen tieri & Morgan, 1996; Freeman et al., 1991; Joseph, Tager -Flushbery, & Lord, 2002; Lovaas, 2003; Scheuffgen, Happe, Anderson, & Frith, 2000; Shriver, Allen, & Matthews, 1999; Sigman, 1998). Ten to thirty -seven percent of individuals with autism have a como rbid medical condition (Rutter, Bailey, Bolton, & Le Couteur, 1994). Autism is considered a neurodevelopmental disorder (Bailey, Phillips & Rutter, 1996) that is biologically mediated. However, there is no clear mode of inheritance and no reliable biomarke rs have been identified ( Dawson, 2007). Comprehensive reviews of the evidence for genetic and biological evidence for autism have been written (e.g., Volkmar, Paul, Klin, & Cohen, 2005). The purpose of this paper is to review the behavior analytic theories of autism and evidence related to them. A review of the theories and research related to them may stimulate further research on understanding the characteristics of autism from a behavior analytic perspective, which may in turn lead to more targe ted interventions.

Presence and absence of stimulus control in temporally defined schedules

The present experiment evaluated the development of stimulus control in temporally defined schedules. Pigeons received reinforcement for the first key-peck in the presence of a nine-dot pattern in tD subcycle, whereas pecks at the same dot pattern as well as six other ones (test stimuli) were extinguished during t∆ subcycle. Across different groups test stimuli were presented at the beginning, at the middle, and at the end of t∆. Sharp and symmetrical gradients were observed with test stimuli at the beginning and at the middle of t∆, whereas higher flat or asymmetrical gradients were observed at the end of t∆. These results do not support the idea that limited-hold contingencies or correlated effects prevent stimulus control.

On the development of stimulus control.

Pigeons were trained to peck one key when presented with white noise at any of five intensities lower than a reference intensity, and to peck another key when presented with white noise at any of five intensities greater than the reference intensity. The shape of the stimulus control curves (proportion of responses to one key versus stimulus intensity) changed from a horizontal line at the beginning of training to the sigmoid form of typical psychometric functions at the end of training. The development of stimulus control is described in terms of a model based on the theory of signal recognition and a concept of attention.

Attention in the pigeon: Testing with compounds or elements

Pigeons received free-operant go no go discrimination training in which the positive stimulus for all subjects was a visual compound, a vertical white line on a blue background. After discrimination training, two types of test trials (“elements”: blue, green, vertical, horizontal; “compounds”: blue-vertical, blue-horizontal, green-vertical, green-horizontal) were presented to each subject during extinction. Under most conditions both kinds of trials revealed that responding was more strongly controlled by wavelength than by line-till. However, only compound trials proved sensitive enough to consistently reveal differential control within the weaker (line-tilt) dimension; the near-zero response output to vertical or horizontal lines presented alone on the “elements” trials made it very difficult to detect any differential line-tilt control and could have led to the erroneous conclusion that some birds had not attended at all to the line-tilt dimension. Other comparisons from the present experiments provided information on “blocking” effects and on the influence of different negative stimuli in the development of stimulus control along the wavelength and line-tilt dimensions.

PROBABILITY OF REINFORCEMENT AND THE DEVELOPMENT OF STIMULUS CONTROL1

Pigeons were trained with a successive discrimination procedure in which responding during the negative stimulus was never reinforced and responding during the positive stimulus was reinforced according to one of four probability values. This discrimination training followed extensive training with a single, neutral stimulus and the same temporal distribution of reinforcements. The development of stimulus control was studied by tracing the difference in rate of responding between the positive and negative stimuli over the course of discrimination training. Response rate during the positive stimulus remained constant, while that during the negative stimulus decreased to zero. The probability of reinforcement associated with the positive stimulus affected both the total number of responses emitted during the negative stimulus and the number of negative stimulus presentations during which responding occurred. However, the number of reinforcements during the positive stimulus preceding the attainment of various degrees of stimulus control was similar for all probability values.

REPEATED MEASUREMENTS OF REINFORCEMENT SCHEDULE EFFECTS ON GRADIENTS OF STIMULUS CONTROL1

Two experiments studied the effects of reinforcement schedules on generalization gradients. In Exp. 1, after pigeons' responding to a vertical line was reinforced, the pigeons were tested with 10 lines differing in orientation. Reconditioning and the redetermination of generalization gradients were repeated from 8 to 11 times with the schedule of reinforcement varied in the reconditioning phase. Stable gradients could not be observed because the successive reconditionings and tests steepened the gradients and reduced responding. Experiment 2 over-came these effects by first training the birds to respond to all of the stimuli. Then, brief periods of reinforced responding to the stimulus correlated with reinforcement alternated with the presentation of the 10 lines in extinction. The development of stimulus control was studied eight times with each bird, twice with each of four schedules of reinforcement. Gradients were similar each time a schedule was imposed; the degree of control by the stimulus correlated with reinforcement varied with particular schedules. Behavioral contrast occurred when periods of reinforcement and extinction alternated and was more durable with fixed-interval, variable-interval, and variable-ratio schedules than with fixed-ratio or differential-reinforcement-of-low-rate schedules.

Role of preexperimental experience in the development of stimulus control.

Role of preexperimental experience in the development of stimulus control.

The development of stimulus control in a three-member chained schedule

Following VI training to peck a “blank” key, two groups of 10 pigeons each were trained for 20 days with a chained schedule (chain VI 40 sec, VI 40 sec, VI 40 sec). For Group 1 the stimulus sequence was: (S3) blank key, (S2) white line, and (S1) a 555mu light, which was reinforced. For Group 2, S2 and S1 were reversed.Generalization tests administered after 5 and 20 chain-training sessions indicated: (a) differences in response rate to S1 and S2 which had developed in training were maintained in extinction, (b) a reliable generalization gradient was present with only S1 after five training days but was present in both stimulus positions after 20 days.