Afterimages: a tool for defining the neural correlate of visual consciousness

Our visual system not only mediates information about the visual environment but is capable of generating pictures of nonexistent worlds: afterimages, illusions, phosphenes, etc. We are "aware" of these pictures just as we are aware of the images of natural, physical objects. This raises the question: is the neural correlate of consciousness (NCC) of such images the same as that of images of physical objects? Images of natural objects have some properties in common with afterimages (e.g., stability of verticality) but there are also obvious differences (e.g., images maintain size constancy, whereas afterimages follow Emmert's Law: when seen while screens at different distances are observed, an afterimage looks larger, the greater the distance of the screen). The differences can be explained by differences in the retinal extent of images and afterimages, which favors the view that both have the same NCC. It seems reasonable to assume that before neural activity can produce awareness, all the computations necessary for a veridical representation of, e.g., an object, must be completed within the neural substrate and that information characteristic of a particular object must be available within the NCC. Given these assumptions, it can be shown that no retinotopic (in a strict sense) cortical areas can serve as the NCC, although some type of topographic representation is necessary. It seems also to be unlikely that neurons classified as cardinal cells alone can serve as NCC.     

EXTINCTION OF SELF-INJURIOUS ESCAPE BEHAVIOR WITH AND WITHOUT INSTRUCTIONAL FADING

Three individuals with developmental disabilities participated in a study of the treatment of self-injurious behavior (SIB) maintained by negative reinforcement (escape from educational tasks). Treatment was implemented in a multiple baseline design across subjects, in which two treatments were compared in a multielement format. Both treatment conditions included an escape-extinction component in which SIB no longer produced escape. One of the conditions also included a fading component in which the frequency of instructions was initially reduced to zero and then was gradually faded back in across sessions until the instructional rate matched that of the original baseline. Results indicated that extinction alone reduced SIB to the end-of-treatment criterion in fewer sessions than did extinction plus fading for all 3 subjects. For 2 of the 3 subjects, however, there was an initial increase in the frequency of SIB at the outset of treatment with extinction (an extinction burst) that was not observed when extinction was combined with the fading component.     

REDUCTION OF SEVERE BEHAVIOR PROBLEMS IN THE COMMUNITY USING A MULTICOMPONENT TREATMENT APPROACH

Problem behavior often prevents community integration of people with developmental disabilities. Therefore, we evaluated a multicomponent approach for remediating problem behavior in public community settings (specifically, supermarkets). We selected treatments based on hypotheses about the variables controlling the problem behavior (hypothesis-driven model). The multicomponent intervention included choice making, embedding, functional communication training, building tolerance for delay of reinforcement, and presenting discriminative stimuli for nonproblem behavior. Treatment progress was monitored using measures of latency and task completion rather than traditional measures of frequency and time sampling. Results showed substantial increases in task completion and duration of time spent in supermarkets without problem behavior. Outcomes were socially validated by group-home staff and cashiers. We discuss how the intervention approach taken can resolve some of the issues involved in assessing, measuring, and treating problem behavior in the community.     

Teaching communicative alternatives to socially withdrawn behavior: An investigation in maintaining treatment effects

This study examined the effectiveness of a contextual intervention strategy paired with an existing packaged intervention on the ability to produce increased and durable social involvement among children who displayed socially withdrawn behavior and their peers. Using a multiple baseline design across three socially withdrawn subjects, results indicated that the combination intervention effectively increased social interactions. Results also indicated that the effects of the intervention maintained two months after intervention termination. General implications for the use of the contextual intervention strategy to produce durable treatment outcomes are discussed.     

EVALUATION OF THE “CONTROL OVER REINFORCEMENT” COMPONENT IN FUNCTIONAL COMMUNICATION TRAINING

The effectiveness of functional communication training (FCT) as a treatment for behavior disorders has been attributed to a number of variables, one of which is the individual's ability to exert control over the delivery of reinforcement. We evaluated this component of FCT by exposing individuals to conditions in which their behavior either did or did not affect the delivery of reinforcement. Three adults with mental retardation who engaged in self-injurious behavior (SIB) participated. Following a functional analysis of their SIB, the effects of FCT were compared to those of noncontingent reinforcement (NCR) in a multielement design. The amount of reinforcement during both conditions was equated by yoking the schedule of reinforcement during NCR sessions to that in effect during FCT sessions. Results indicated that FCT and NCR were equally effective in reducing the SIB of all participants and suggest that control over reinforcement delivery may not affect the degree to which FCT produces behavioral suppression. However, a different benefit of FCT was evident in the results: More consistent increases in the alternative response were observed during the FCT condition than during the NCR condition.     

Assessment-based intervention for severe behavior problems in a natural family context.

Functional assessments and assessment-based interventions were conducted with a boy with disabilities and severe problem behavior in the context of two family routines: using the bathroom in the family home and dining in a fast-food restaurant. A multiple baseline design demonstrated the effectiveness of the intervention package as implemented by the boy's mother in the two routines. The results provide a systematic replication and extension of behavior-analytic interventions in natural family contexts.     

The evaluation and treatment of aggression maintained by attention and automatic reinforcement.

In the current investigation, we used direct and indirect methods to assess and treat several topographies of aggression that were hypothesized to have separate operant functions in a young boy with severe mental retardation and pervasive developmental disorder. First, a functional analysis of aggression, using the methods described by Iwata, Dorsey, Slifer, Bauman, and Richman (1982/1994), was conducted and produced inconclusive results. Next, indirect methods were used to develop a second functional analysis, which showed that chin grinding (firmly pressing and grinding his chin against the skin and bones of others) persisted independent of social contingencies and that the other topographies of aggression (e.g., hitting, kicking) were maintained by social positive reinforcement (attention). A treatment designed to decrease aggression maintained by attention—functional communication training with extinction—reduced all forms of aggression except chin grinding. This latter topography of aggression, which we hypothesized was maintained by automatic reinforcement, was reduced when the response-reinforcer relation was interrupted through response blocking and the child was provided with an alternative form of chin stimulation.     

ESTABLISHING DISCRIMINATIVE CONTROL OF RESPONDING USING FUNCTIONAL AND ALTERNATIVE REINFORCERS DURING FUNCTIONAL COMMUNICATION TRAINING

Functional communication training (FCT) is a popular treatment for problem behaviors, but its effectiveness may be compromised when the client emits the target communication response and reinforcement is either delayed or denied. In the current investigation, we trained 2 individuals to emit different communication responses to request (a) the reinforcer for destructive behavior in a given situation (e.g., contingent attention in the attention condition of a functional analysis) and (b) an alternative reinforcer (e.g., toys in the attention condition of a functional analysis). Next, we taught the participants to request each reinforcer in the presence of a different discriminative stimulus (S^D). Then, we evaluated the effects of differential reinforcement of communication (DRC) using the functional and alternative reinforcers and correlated S^Ds, with and without extinction of destructive behavior. During all applications, DRC (in combination with S^Ds that signaled available reinforcers) rapidly reduced destructive behavior to low levels regardless of whether the functional reinforcer or an alternative reinforcer was available or whether reinforcement for destructive behavior was discontinued (i.e., extinction).     

Assessment of Potential,from Assessment Centers to Development Centers

Are organizations interested in realizing the potential of their employees? How far have they progressed in utilizing performance assessment instruments for developmental purposes? There is a growing need for redirecting organizations towards greater knowledge productivity and using the competencies of their employees in a knowledge-productive way. Development centers provide possibilities for analyzing and diagnosing the relevant competencies of personnel whilst at the same time, providing a match with further development. This study examines managers’ attitudes towards assessment centers and their potential to be used for developmental purposes. The problems and processes involved in using assessment centers in this way were studied within a representative set of large, Dutch organizations. In addition, the conceptions of management and the implementation conditions needed for the introduction of development centers were examined. The advantages of development centers as a knowledge-productive tool for assessment in organizations are discussed to help managers decide about developmental programs.     

Gyral morphology in the posterior Sylvian region in families affected by developmental language disorder

This study describes the family aggregation of gyral morphology in the posterior perisylvian region in families that contain one or more children with a developmental language disorder. The probands in these families were 8 male and 2 female children referred through therapy programs and schools for children with language and reading problems. Family members included both biological parents (10 m, 10 f) and all available siblings (6 m, 4 f). Gyral morphology in the members of these families was compared with control subjects (10 m, 10 f) who were without a personal or family history of developmental language disorders. Gyral morphology was evaluated using T1-weighted sagittal scans from a GE Signa 1.5T magnet, 5 mm consecutive slices through the full brain volume. A less common type of Sylvian fissure morphology was more frequently found in the hemispheres of language-disordered subjects and their first-degree relatives than in control subjects. In addition, the pattern of Sylvian fissure morphology across generations within the families suggests that this feature might be inherited from either parent. The elevated rate of extra gyri in the posterior perisylvian region in families affected by language disorder links an anomaly within a language-related brain region with familial risk for this disorder.