Premise Misinterpretation and Syllogistic Reasoning

A study by Ceraso and Provitera (1971) found that elaboration of the premises used in syllogistic reasoning led to substantially improved performance. This finding is of considerable importance because of the implications it has for mental logic and mental models theories of reasoning. Three experiments are reported, which replicated and extended the original findings. It was found that elaboration led to a significant improvement in performance, but that this was confined to multiple model syllogisms, where the elaboration has the effect of reducing the number of models involved. A fourth experiment indicated that elaboration can vary within the same syllogism depending on the direction of the conclusion drawn. These findings are best explained under the assumption that reasoners build mental models when solving problems and that elaboration can reduce the number of possible models.     

Linkages between childhood executive functioning and adolescent social functioning and psychopathology in girls with ADHD

We followed an ethnically and socioeconomically diverse sample of preadolescent girls with ADHD (n = 140) and matched comparison girls (n = 88) over a period of 5 years, from middle childhood through early/midadolescence, with the aim of determining whether childhood levels of executive function (EF) would predict adolescent multi-informant outcomes of social functioning and psychopathology, including comorbidity between externalizing and internalizing symptomatology. Predictors were well-established measures of planning, response inhibition, and working memory, along with a control measure of fine motor control. Independent of ADHD versus comparison group status, (a) childhood planning and response inhibition predicted adolescent social functioning and (b) childhood planning predicted comorbid internalizing/externalizing disorders in adolescence. Subgroup status (ADHD-Combined, ADHD-Inattentive, and comparison) moderated the relationship between childhood planning and adolescent internalizing/externalizing comorbidity, with the combined type revealing particularly strong associations between baseline planning and adolescent comorbidity. Mediation analyses indicated that adolescent social functioning mediated the prediction from childhood EF to comorbidity at follow-up; in turn, in the girls with ADHD, adolescent comorbidity mediated the prediction from childhood EF to social functioning at follow-up. We conclude that childhood interventions should target EF impairments in addition to behavioral symptoms.     

Touch screen assays of behavioural flexibility and error characteristics in Eastern grey squirrels (<Emphasis Type="Italic">Sciurus carolinensis</Emphasis>)

Behavioural flexibility allows animals to adjust their behaviours according to changing environmental demands. Such flexibility is frequently assessed by the discrimination–reversal learning task. We examined grey squirrels’ behavioural flexibility, using a simultaneous colour discrimination–reversal learning task on a touch screen. Squirrels were trained to select their non-preferred colour in the discrimination phase, and their preferred colour was rewarded in a subsequent reversal phase. We used error rates to divide learning in each phase into three stages (perseveration, chance level and ‘learned’) and examined response inhibition and head-switching during each stage. We found consistent behavioural patterns were associated with each learning stage: in the perseveration stage, at the beginning of each training phase, squirrels showed comparable response latencies to correct and incorrect stimuli, along with a low level of head-switching. They quickly overcame perseveration, typically in one to three training blocks. In the chance-level stage, response latencies to both stimuli were low, but during initial discrimination squirrels showed more head-switches than in the previous stage. This suggests that squirrels were learning the current reward contingency by responding rapidly to a stimulus, but with increased attention to both stimuli. In the learned stage, response latencies to the correct stimulus and the number of head-switches were at their highest, whereas incorrect response latencies were at their lowest, and differed significantly from correct response latencies. These results suggest increased response inhibition and attention allowed the squirrels to minimise errors. They also suggest that errors in the ‘learned’ stage were related to impulsive emission of the pre-potent or previously learned responses.     

Can simultaneous speech stimuli be classified in parallel?

Reaction times to detect a known or unknown digit in paired or single auditory test stimuli were measured. The results suggest that in classification or matching tasks with stimuli belonging to separate verbal classes, parallel or selective processing may be possible. There was no interaction of type of task (classify vs match) with either dichotic vs mixed monaural presentation, or pairs vs single stimuli, or negative vs positive responses. An attempt was made to suggest the separate processing stages underlying performance in this task.     

When is early visual cortex activated during visual mental imagery?

Although many neuroimaging studies of visual mental imagery have revealed activation in early visual cortex (Areas 17 or 18), many others have not. The authors review this literature and compare how well 3 models explain the disparate results. Each study was coded 1 or 0, indicating whether activation in early visual cortex was observed, and sets of variables associated with each model were fit to the observed results using logistic regression analysis. Three variables predicted all of the systematic differences in the probability of activation across studies. Two of these variables were identified with a perceptual anticipation theory, and the other was identified with a methodological factors theory. Thus, the variability in the literature is not random.