Genetic Studies of Autism: From the 1970s into the Millennium

Reviewers in the 1960s and early 1970s were skeptical about any substantial role for genetic factors in the etiology of autism. A realization that the 2% rate of autism in siblings (as estimated at that time) was far above the general population base rate, and that this suggested a possible high genetic liability, led to the first small-scale twin study of autism. The replicated evidence from both twin and family studies undertaken in the 1970s and 1980s indicated both strong genetic influences and the likelihood that they applied to a phenotype that was much broader than the traditional diagnostic category of autism. Medical and chromosomal findings also indicated genetic heterogeneity. Advances in molecular genetics led to genome-wide scans of affected relative pair samples with a positive log of the odds to base 10 score for a location on chromosome 7. The major remaining research challenges and the likely clinical benefits that should derive from genetic research are considered in relation to both current knowledge and that anticipated to emerge from research over the next decade.     

Barking up the wrong tree? Lexical ambiguity resolution in children with language impairments and autistic spectrum disorders

Lexical ambiguity resolution was investigated in 9- to 17-year-olds with language impairment (LI, n=20), autistic spectrum disorder (ASD) plus language impairment (ALI, n=28), ASD and verbal abilities within the normal range (ASO, n=20), and typically developing children (TD, n=28). Experiment 1 investigated knowledge of dominant and subordinate meanings of ambiguous words. The LI and ALI groups knew fewer subordinate meanings than did the ASO and TD groups. Experiment 2 used a modified version of the paradigm to investigate contextual facilitation and suppression of irrelevant meanings. All groups demonstrated contextual facilitation, responding quickly and more accurately to words following a biased context. However, children with ALI and LI did not use context as efficiently as did their peers without language deficit. Furthermore, for the LI and ALI groups, errors in the suppression condition reflected poor contextual processing. These findings challenge the assumptions of weak central coherence theory and demonstrate the need for stringent language controls in the study of autistic cognition.     

Distinguishing Between Causes and Enabling Conditions—Through Mental Models or Linguistic Cues?

The mental model theory of naive causal understanding and reasoning (Goldvarg & Johnson-Laird, 2001, Cognitive Science, 25, 565–610) claims that people distinguish between causes and enabling conditions on the basis of sets of models that represent possible causal situations. In the tasks used to test this hypothesis, however, the proposed set of models was confounded with linguistic cues that frame which event to assume as given (the enabling condition) and which to consider as responsible for the effect under this assumption (the cause). By disentangling these two factors, we were able to show that when identifying causes and enabling conditions in these tasks, people rely strongly on the linguistic cues but not on the proposed set of models and that this set of models does not even reflect people's typical interpretation of the tasks. We propose an alternative explanation that integrates syntactic and causal considerations.     

Who are the comorbid adolescents? Agreement between psychiatric diagnosis,youth, parent,and teacher report

The investigators examined the rates of psychiatric comorbidity for externalizing and internalizing behavior problems, using semistructured diagnostic interview and parent, teacher, and youth report on the Achenbach checklists. The study also evaluated the effects of conjunctive, compensatory, and disjunctive data combination strategies. Using the same data and identical diagnostic thresholds, between 5 and 74% of 189 youths presenting to an outpatient clinic were identified as having comorbid internalizing and externalizing problems. Parent report and semistructured interview indicated the highest comorbidity rates. Despite good cross-source agreement (rs .29–.58), there was very little agreement about which specific youths presented with comorbid internalizing and externalizing problems (kappas .14–.40). Results also indicate that single DSM-IV disorders, such as bipolar disorder, can manifest comorbid patterns of behavior problems on checklists.     

Tests of sphericity of normal distributions and the analysis of repeated measures designs

The locally best invariant test statistic for testing sphericity of normal distributions is shown to be a simple function of the Box/Geisser-Greenhouse degrees of freedom correction factor in a repeated measures design. Because of this relationship it provides a more intuitively appealing test of the necessary and sufficient conditions for valid F-tests in repeated measures analysis of variance than the likelihood ratio test. The properties of the two tests are compared and tables of the critical values of the Box/Geisser-Greenhouse correction factor are given.     

A CLASSIFICATION SCHEME OF SOCIAL CONDITIONS OF REINFORCEMENT WITHIN GROUP OPERANT SYSTEMS1

Many different reinforcement contingencies are found in group operant systems, such as token economies and point systems. Some systems use group contingencies in which the reinforcement of any one participant may depend on the behavior of some other group member. Other programs are individual, in that participants earn reinforcers dependent only on their own behavior. The various possible arrangements of people and their response requirements are labelled “social conditions of reinforcement” in this paper. Previous attempts at classification have failed to categorize the variety of social conditions of reinforcement. In addition, some conditions that may produce behaviorally different effects have not been separated. The present paper classifies the social conditions of reinforcement found in applied programs in a three-dimensional scheme. The efficacy of the three major dimensions—reinforcing agent, recipient response requirement, and group response requirement—is supported by clinical and research data. The reinforcing agent dimension refers to the person(s) who dispenses reinforcers to group members. This major dimension is further subdivided: one or several agents may be either designated or nondesignated. Recipients are the group members who receive reinforcement. This dimension is also subdivided: one or several recipients in a social condition of reinforcement may obtain reinforcers either contingently or noncontingently. The group response requirement is a criterion that must be satisfied before any group participant is eligible for reinforcement. Some systems have no group requirement, and others have a group requirement that must be met by some designated or nondesignated participant(s). Supportive references and examples are given in the explanation of each dimension and subdimension. The behavioral impact of the various categories is emphasized. For all major dimensions, applied implications and research suggestions are discussed. Concluding remarks center on the utility of the present scheme, the classification of operant procedures other than positive reinforcement, and both theoretical and applied issues requiring further study (e.g., the long-term effects of participation in group contingencies).     

Effects on choice of reinforcement delay and conditioned reinforcement

Pigeons chose between fixed-interval schedules of different durations presented in the terminal links of concurrent-chains schedules. The pair of schedules was always in the ratio of 2:1, but the absolute duration of the fixed intervals varied. In one set of conditions, the different terminal-link schedules were associated with different keylight stimuli (cued conditions). In a second set of conditions, the different terminal-link schedules were associated with the same stimulus (uncued conditions). Results from the cued conditions replicated previous findings that preference for the shorter fixed-interval schedule increased with fixed-interval duration. Preferences in the uncued conditions were lower than in the corresponding cued conditions but also increased with fixed-interval length. In addition, the degree of control under the uncued conditions was correlated with the extent to which the schedule during the terminal link was discriminated immediately upon entry into the terminal link. The pattern of results in both conditions was inconsistent with the notion that choice behavior matches relative immediacy of reinforcement. Reanalysis of previous evidence for matching (Chung and Herrnstein, 1967) showed that matching in fact did not occur, as the preferences of their subjects for the shorter of two delays also increased with the absolute size of the delays.     

Autistic camouflaging across the spectrum

Camouflaging may be characterized as a set of actions and strategies more or less consciously adopted by some autistic people to navigate the neurotypical social world. Despite the increased interest that this phenomenon has garnered, its nature remains elusive and in need of conceptual clarification. In this paper, we aim to put forward an inclusive view of camouflaging that does justice to its complexity while also reflecting the heterogeneity of autism as a condition. First, we offer an overview of the main characterizations of camouflaging. This overview shows that current characterizations fail to paint a cohesive picture, and that different accounts emphasize different aspects of the phenomenon. Second, we explore the analogy between camouflaging and passing, which we take to be illuminating to describe some forms of camouflaging, while probably obscuring the study of others. Third, we extend the discussion about camouflaging to currently understudied groups across the autistic spectrum – i.e., children, and adults with linguistic and/or intellectual disabilities. We argue that camouflaging in such groups may differ from what the current literature describes as typical instances of camouflaging. We conclude by revisiting the nature of camouflaging in light of such understudied groups, and we offer some suggestions on how to move research forward.     

Caregiver-implemented toilet training procedures for children with autism spectrum disorder

Children with Autism Spectrum Disorder often exhibit deficits in daily living skills, including toileting skills. Previous studies have evaluated components of common toilet training practices, including differential reinforcement, sit schedules, fluid loading, underwear, and wet alarms. The purpose of this study was to replicate and extend previous work by delivering all coaching remotely. Three caregiver-child dyads participated in this study. A researcher coached caregivers on the implementation of the protocol using a modified behavioral skills training approach via telehealth. Caregivers submitted daily toileting data and weekly audio recordings for treatment integrity checks. The sit schedule fading was individualized to meet the needs and preferences of each family. All caregivers implemented the protocol with high integrity. Two participants met the mastery criteria at the 90-min sit schedule and maintained performance at the 1- and 6-week maintenance follow up probes. The third participant, despite an interruption of treatment, also reached mastery.