Neurobiological Markers of Illness Onset in Psychosis and Schizophrenia: The Search for a Moving Target

In this review, we describe neuropsychological and brain imaging findings in the early stages of psychosis and schizophrenia. We focus on recent clinical high-risk studies and consider whether the evidence supports these as ‘endophenotypes’ of a vulnerability to the illness or as ‘biomarkers’ of illness onset and transition. The findings suggest that there are a number of processes at psychosis onset that may represent biomarkers of incipient illness. These neurobiological indices particularly implicate the integrity of frontal and temporal cortices, which may or may not be related to the genetics of psychosis (i.e. potential ‘endophenotypes’). However, these brain regions are dynamically changing during normal maturation, meaning that any putative neurobiological markers identified at the earliest stages of illness may be relatively unstable. We suggest that, while such measures may be readily identified as potential neurobiological markers of established illness, they are inconsistent at (or around) the time of illness onset when assessed cross-sectionally. Instead, identification of more valid risk markers may require longitudinal assessment to ascertain normal or abnormal trajectories of neurodevelopment. Accordingly, we assert that the current conceptualisations of potential biomarkers and/or ‘endophenotypes’ for schizophrenia may need to be reconsidered in the context of normal and abnormal brain maturational processes at the time of onset of psychotic disorders.     

Do Colours Look Like Dispositions? Reply to Langsam and Others

Dispositional theories of colour have been attacked by McGinn and others on the ground that 'Colours do not look like dispositions'. Langsam has argued that on the contrary they do, in 'Why Colours Do Look Like Dispositions', The Philosophical Quarterly , 50 (2000), pp. 68–75. I make three claims. First, neither side has made its case. Secondly, it is true, at least on one interpretation, that colours do not look like dispositions. Thirdly, this does not show that dispositionalism about colours is false.     

Parafoveal-on-foveal interactions in word recognition

An experiment is reported in which participants read sequences of five words, looking for items describing articles of clothing. The third and fourth words in critical sequences were defined as "foveal" and "parafoveal" words, respectively. The length and frequency of foveal words and the length, frequency, and initial-letter constraint of parafoveal words were manipulated. Gaze and refixation rate on the foveal word were measured as a function of properties of the parafoveal word. The results show that measured gaze on a given foveal word is systematically modulated by properties of an unfixated parafoveal word. It is suggested that apparent inconsistencies in previous studies of parafoveal-on-foveal effects relate to a failure to control for foveal word length and hence the visibility of parafoveal words. A serial-sequential attention-switching model of eye movement control cannot account for the pattern of obtained effects. The data are also incompatible with various forms of parallel-processing model. They are best accounted for by postulating a process-monitoring mechanism, sensitive to the simultaneous rate of acquisition of information from foveal and parafoveal sources.     

Reducing the serious behavior problems of people with developmental disabilities living in the community

Trends and issues regarding the community-based support of people with developmental disabilities who exhibit severe behavior problems are discussed. Living in the community provides a unique framework within which behavior change programs are developed, implemented, and monitored. Support models for people with challenging behavior need to: (a) program for diversity across people, settings, and activities; (b) plan for high levels of integration in community settings among typical community members; and (c) meet guidelines regarding restrictions in intervention typologies. Increasingly, behavior analysts are conducting analog and in vivo assessments prior to intervening in order to develop an understanding of why behavior problems are occurring. Along with the increase in assessing the functions of behavior, is a greater attention to the contexts in which interventions are applied. The rearranging of contexts, communication training, choice-making, matching people's competence to their settings, the use of novelty, and proactive programing reflect these concerns.     

SLEEP DEPRIVATION,ALLERGY SYMPTOMS,AND NEGATIVELY REINFORCED PROBLEM BEHAVIOR

We studied the relation between the presence versus the absence of sleep deprivation or allergy symptoms and the rate and function of problem behavior. Three students whose problem behavior was negatively reinforced by escape from instruction were studied across several weeks using analogue functional analyses. Our results indicated that the extraexperimental events were associated with (a) termination of instruction functioning as a negative reinforcer, (b) increased rates of negatively reinforced problem behavior, or (c) increased rates of problem behavior across all conditions.     

General Education Participation Improves the Social Contacts and Friendship Networks of Students with Severe Disabilities

One desired outcome of inclusive education is the enhanced social development of students with disabilities. Some have suggested that planned and systematic support of students with severe disabilities in general education environments may lead to greater social interaction between these students and their peers without disabilities. In an effort to analyze this proposition, we studied two students with severe disabilities as they began participating in general education classrooms. Using within-student multiple baseline designs across class periods, the effects of participating in general education were studied across a range of social participation indicator variables. Our results suggest that planned and systematic efforts to include students with severe disabilities into general education courses can have positive effects on their social contacts and friendship networks. Our findings are discussed in relation to policy efforts to establish inclusive education in public schools, strategies for structuring general education participation, and the potential effects such efforts can have on the social inclusion of students with disabilities.