Speech disfluencies occur frequently in spontaneous speech but their source is unclear. Disfluencies can take severalforms, most commonly as verbalized disfluencies such as “um”, “uh”, and “so”, as well as silent pauses. In the presentexploratory study we examined the relationship between disfluencies as distinct entities, individual differences in workingmemory capacity, and linguistic markers of complexity. We found that disfluencies diverge in their relationship with thesevariables. The “um” disfluency was most closely related to working memory capacity and linguistic complexity. The “uh”disfluency was associated with infrequent word production. The “so” disfluency predicted of the number of words produced.Silent disfluencies were not related to working memory capacity. However, micro-pauses were related to word production,and macro-pauses were negatively correlated with the “so” disfluency. Results are discussed in terms of potential relationshipsbetween disfluencies and speech production processes.

The goal of the present study was to demonstrate the potentialapplication of Item Response Theory (IRT) outside itstraditional use in assessing questionnaires by applying it todata from behavioural task. We did this by validating aperspective taking task called the Director Task used to assessTheory of Mind (ToM) abilities in young adults. IRT andconvergent validity analyses indicated that, contrary to ourhypotheses, the Director Task had an unduly narrow range ofresponding for measuring ToM. Furthermore, the DirectorTask did not correlate with other established measures ofToM. Our results suggest that the task should be used withcaution when assessing a young adult population.Furthermore, since convergent validity was not established, itis uncertain what specifically the task measures. Overall, weshow how IRT may serve as a useful tool in evaluatingbehavioural measures.

Psychopaths have long been associated with a unique abilityto manipulate others (Hare, 1999). According to the“bottleneck” hypothesis of psychopathy (Newman & Baskin-Sommers, 2012), psychopaths’ cognitive abilities are directlyrelated to goal-directed behavior. To shed more light onlanguage production in psychopathy, two languageproduction studies were completed contrasting content andfluency under different motivational and difficulty conditions.Individuals high in psychopathy (HP) were less fluent butmaintained a more complex lexicon than their lowpsychopathy (LP) counterparts when under high cognitiveload and low motivation. Yet when HP individuals were underlow cognitive load and high motivation, they were morefluent, but used a less complex lexicon. Furthermore, the HPgroup produced more emotional language in both conditions.The results suggest that HP individuals’ language productionis inherently related to motivation and they attempt to balancefluency and complexity when cognitive load is increased.