A preliminary examination of the evocative effects of the establishing operation

We attempted to isolate the evocative effects of the establishing operation for positively reinforced problem behavior with 2 participants. The study consisted of three phases. First, a functional analysis identified tangible items (Participant 1) and attention (Participant 2) as maintaining problem behavior. Second, access to tangible items and attention was systematically controlled (continuous access vs. no access) immediately prior to functional analysis sessions in which these consequences were delivered contingent on problem behavior. Results of this phase indicated that problem behavior occurred at higher levels when access to tangible items and attention was restricted. In the third phase, prior access was again controlled, but problem behavior produced no consequences. Results of this final phase indicated that problem behavior occurred at higher levels during extinction sessions when participants did not have prior access to the reinforcers.     

Release from generation failure: The role of study list structure

Three experiments, using the original encoding-specificity paradigm, investigated the role of study list structure in producing Higham and Tam's (2005) generation failure effect. Generation failure occurs when cued recall performance for strong, extralist cues is worse than target production in a control group that is given no study list but is instead required merely to generate responses to the same test cues. In the present study, generation failure was replicated in Experiment 1, and Experiment 2 demonstrated that strong, extralist cues were more likely to elicit targets in pure generation groups when participants had studied a list of strong associates than when they had studied a list of weak ones. In Experiment 3, participants were released from generation failure when a study list of moderate associates was used and the cue-to-target associative strength was equated between the reinstated- and extralist-cue conditions. Together, these results suggest that generation failure is partly attributable to participants' searching inappropriate domains that, though consistent with the study list structure, are unlikely to contain targets.     

Moving up from the segment: a comment on Aichert and Ziegler's syllable frequency and syllable structure in apraxia of speech, Brain and Language, 88, 148-159, 2004

In a recent article, explore whether apraxia of speech (AOS) can be explained by disruption of the phonetic plans for high frequency syllables. This approach is a hybrid one, combining the notion of a mental syllabary with an explanation that the impairment in AOS results from reduced access to supra-segmental phonetic plans. In this commentary, we explore Aichert and Ziegler's approach and suggest that in testing a hybrid model it is important to be cautious in identifying implications for the two source models.     

The epidemiology of mental retardation: challenges and opportunities in the new millennium

There are a number of problems and challenges in relating the science of epidemiology to mental retardation (MR). These relate to how MR is defined and classified and how these definitions may change over time. These as well as other differences in ascertainment sources and methods need to be considered when comparing MR prevalence over time and place. On the other hand, advances in technology also provide new and efficient methods of data collection both by data linkage and by use of web-based methods to study rare diseases. While prevalence studies have not been individually reviewed, we have examined the range of data including recent studies relating to how prevalence differs according to age, gender, social class and ethnicity. Some problems with available etiological classification systems have been identified. Recent etiological studies, most of which use different classification systems, have been reviewed and explanations have been postulated to account for differences in results. Individual risk factors for MR are considered whilst the option of considering a population as opposed to a high risk strategy to MR prevention is raised. This might well involve improving the social milieu surrounding the occurrence of individual risk factors. The impact of biotechnological advances such as antenatal and neonatal screening and assisted reproduction on MR are discussed. The issue of how inequalities in access to technology may impact on case identification and even have the potential to further widen inequalities is raised. The importance of extending the use of epidemiological tools to study the social, health and economic burden of MR is also emphasized. However, in order to apply to MR the "prevention-intervention-research" cycle, which surely underpins all epidemiology, it is vital to ensure that the methodological challenges we raise are adequately addressed.     

Hemispheric contributions to lexical ambiguity resolution: evidence from individuals with complex language impairment following left-hemisphere lesions

Nine individuals with complex language deficits following left-hemisphere cortical lesions and a matched control group (n = 9) performed speeded lexical decisions on the third word of auditory word triplets containing a lexical ambiguity. The critical conditions were concordant (e.g., coin-bank-money), discordant (e.g., river-bank-money), neutral (e.g., day-bank-money), and unrelated (e.g., river-day-money). Triplets were presented with an interstimulus interval (ISI) of 100 and 1250 ms. Overall, the left-hemisphere-damaged subjects appeared able to exhaustively access meanings for lexical ambiguities rapidly, but were unable to reduce the level of activation for contextually inappropriate meanings at both short and long ISIs, unlike control subjects. These findings are consistent with a disruption of the proposed role of the left hemisphere in selecting and suppressing meanings via contextual integration and a sparing of the right-hemisphere mechanisms responsible for maintaining alternative meanings.     

An on-line investigation of lexical ambiguity processing in schizophrenia

The processing of lexical ambiguity in context was investigated in eight individuals with schizophrenia and a matched control group. Participants made speeded lexical decisions on the third word in auditory word triplets representing concordant (coin-bank-money), discordant (river-bank-money), neutral (day-bank-money), and unrelated (river-day-money) conditions. When the interstimulus interval (ISI) between the words was 100 ms, individuals with schizophrenia demonstrated priming consistent with selective, context-based lexical activation. At 1250 ms ISI, a pattern of nonselective meaning facilitation was obtained. These results suggest an attentional breakdown in the sustained inhibition of meanings on the basis of lexical context.