Visual illusions affect both movement planning and on-line control: a multiple cue position on bias and goal-directed action

Over the last decade, there has been an interest in the impact of visual illusions on the control of action. Much of this work has been motivated by Milner and Goodale's two visual system model of visual processing. This model is based on a hypothesized dissociation between cognitive judgments and the visual control of action. It holds that action is immune to the visual context that provides the basis for the illusion-induced bias associated with cognitive judgments. Recently, Glover has challenged this position and has suggested that movement planning, but not movement execution is susceptible to visual illusions. Research from our lab is inconsistent with both models of visual-motor processing. With respect to the planning and control model, kinematic evidence shows that the impact of an illusion on manual aiming increases as the limb approaches the target. For the Ebbinghaus illusion, this involved a decrease in the time after peak velocity to accommodate the 'perceived' size of the target. For the Müller-Lyer illusion, the influence of the figure's tails increased from peak velocity to the end of the movement. Although our findings contradict a strong version of the two visual systems hypothesis, we did find dissociations between perception and action in another experiment. In this Müller-Lyer study, perceptual decisions were influenced by misjudgment of extent, while action was influenced by misjudgment of target position. Overall, our findings are consistent with the idea that it is often necessary to use visual context to make adjustments to ongoing movements.     

Strategic navigation of two-dimensional alley mazes: comparing capuchin monkeys and chimpanzees

Planning is an important component of cognition that contributes, for example, to efficient movement through space. In the current study we presented novel two-dimensional alley mazes to four chimpanzees and three capuchin monkeys to identify the nature and efficiency of planning in relation to varying task parameters. All the subjects solved more mazes without error than expected by chance, providing compelling evidence that both species planned their choices in some manner. The probability of making a correct choice on mazes designed to be more demanding and presented later in the testing series was higher than on earlier, simpler mazes (chimpanzees), or unchanged (capuchin monkeys), suggesting microdevelopment of strategic choice. Structural properties of the mazes affected both species' choices. Capuchin monkeys were less likely than chimpanzees to take a correct path that initially led away from the goal but that eventually led to the goal. Chimpanzees were more likely to make an error by passing a correct path than by turning onto a wrong path. Chimpanzees and one capuchin made more errors on choices farther in sequence from the goal. Each species corrected errors before running into the end of an alley in approximately 40% of cases. Together, these findings suggest nascent planning abilities in each species, and the prospect for significant development of strategic planning capabilities on tasks presenting multiple simultaneous or sequential spatial relations. The computerized maze paradigm appears well suited to investigate movement planning and spatial perception in human and nonhuman primates alike.     

Commitment,ego-involvement,and resistance to attack

Subjects with initially extreme or moderate positions (based on a median split) recorded a consonant speech under public, private, or no commitment and later received a strong, mild, or no attack on their position. Extremes were more ego-involved in terms of wider latitudes of rejection, narrower latitudes of non-commitment, and greater resistance to attack, relative to moderates. Commitment had no effect for extremes, suggesting a ceiling effect on changes in the latitudes and resistance to attack for initially high levels of ego-involvement. For moderates, commitment resulted in narrower latitudes of noncommitment, wider latitudes of rejection (greater rejection of discrepant positions), and greater resistance to attack, suggesting that commitment may elevate ego-involvement with the issue. Commitment and ego-involvement may increase the salience of one's attitude position in later situations, thereby increasing the probability of attitudeconsistent behavior.     

A computational model of frontal lobe dysfunction: working memory and the Tower of Hanoi task

A symbolic computer model, employing the perceptual strategy, is presented for solving Tower of Hanoi problems. The model is calibrated—in terms of the number of problems solved, time taken, and number of moves made—to the performance of 20 normal subjects. It is then "lesioned" by increasing the decay rate of elements in working memory to model the performance of 20 patients with lesions to the prefrontal cortex. The model captures both the main effects of subject groups (patients and normal controls) performance, and the subject groups (patients and normal controls) by problem difficulty interactions. This leads us to support the working memory hypothesis of frontal lobe functions, but for a narrow range of problems.     

Neurocognitive Effects of Methamphetamine: A Critical Review and Meta-analysis

This review provides a critical analysis of the central nervous system effects of acute and chronic methamphetamine (MA) use, which is linked to numerous adverse psychosocial, neuropsychiatric, and medical problems. A meta-analysis of the neuropsychological effects of MA abuse/dependence revealed broadly medium effect sizes, showing deficits in episodic memory, executive functions, information processing speed, motor skills, language, and visuoconstructional abilities. The neuropsychological deficits associated with MA abuse/dependence are interpreted with regard to their possible neural mechanisms, most notably MA-associated frontostriatal neurotoxicity. In addition, potential explanatory factors are considered, including demographics (e.g., gender), MA use characteristics (e.g., duration of abstinence), and the influence of common psychiatric (e.g., other substance-related disorders) and neuromedical (e.g., HIV infection) comorbidities. Finally, these findings are discussed with respect to their potential contribution to the clinical management of persons with MA abuse/dependence.     

The development of strategy use in elementary school children: working memory and individual differences

The current study tested the development of working memory involvement in children's arithmetic strategy selection and strategy efficiency. To this end, an experiment in which the dual-task method and the choice/no-choice method were combined was administered to 10- to 12-year-olds. Working memory was needed in retrieval, transformation, and counting strategies, but the ratio between available working memory resources and arithmetic task demands changed across development. More frequent retrieval use, more efficient memory retrieval, and more efficient counting processes reduced the working memory requirements. Strategy efficiency and strategy selection were also modified by individual differences such as processing speed, arithmetic skill, gender, and math anxiety. Short-term memory capacity, in contrast, was not related to children's strategy selection or strategy efficiency.     

Disorders in planning and strategy application in frontal lobe lesion patients

The aim of this study was to investigate deficits in planning ability using an adapted version of the Modified Six Elements Test, from the Behavioral Assessment of the Dysexecutive Syndrome—BADS [Wilson, B. A., Alderman, N., Burgess, P. W., Emslie, H., & Evans, J. J. (1996). Behavioural Assessment of the Dysexecutive Syndrome (BADS). Bury St Edmunds, U.K.: Thames Valley Test Company. Trans. Ricardo O Souza, Sergio L Schmidt. Rio de Janeiro: Cognição]. Subjects were left- and right-frontal lobe lesion patients. Other measures of executive dysfunctions used were verbal fluency, the Wisconsin Card Sorting Test, and the Trail Making Test. These other instruments were sensitive to detect executive deficits in the left frontal lobe lesion group, except the Wisconsin Card Sorting Test, which showed impairment only for the frontal lobe lesion group as a whole. The Modified Six Elements Test detected planning disorders in left frontal lobe lesion patients. The deficit of these patients was due to a greater likelihood to break the rules of the task, that is, in plan-following processes, rather than in planning the strategic approach to solve it.     

Younger apes and human children plan their moves in a maze task

Planning defined as the predetermination of a sequence of actions towards some goal is crucial for complex problem solving. To shed light on the evolution of executive functions, we investigated the ontogenetic and phylogenetic origins of planning. Therefore, we presented all four great apes species (N = 12) as well as 4- and 5-year-old human preschoolers (N = 24) with a vertical maze task. To gain a reward placed on the uppermost level of the maze, subjects had to move the reward to the bottom through open gaps situated at each level of the maze. In total, there were ten gaps located over three of the maze’s levels, and free passage through these gaps could be flexibly blocked using multiple traps. Due to the decision tree design of the maze, the subjects had to plan their actions depending on the trap configuration up to two steps ahead to successfully retrieve the reward. We found that (1) our measure of planning was negatively correlated with age in nonhuman apes, (2) younger apes as well as 5-year-old children planned their moves up to two steps ahead whereas 4-year-olds were limited to plan one step ahead, and (3) similar performance but different underlying limitations between apes and children. Namely, while all species of nonhuman apes were limited by a lack of motor control, human children exhibited a shortage in shifting their attention across a sequence of subgoals.     

Anglicans and Islam in East Africa: The Diocese of Zanzibar and the Universities’ Mission to Central Africa (1923–63)

This article examines the legacy of Godfrey Dale, who in 1923 published a Qur'an in Swahili, with the intention of letting people “know what the Qur?ān does say.” The work of his successors is explored. It discusses the proposals for work amongst Muslims submitted by lay and ordained members of the Diocese of Zanzibar for consideration at the 1944 Diocesan Conference, as the Diocese prepared for the situation after World War II. Finally, it examines the role of the Diocese with particular reference to Christian–Muslim relations as Tanganyika and Zanzibar prepared for Independence.     

Relationships between general self-efficacy,planning for the future,and life satisfaction

In this study we investigated relationships between general self-efficacy, the propensity to plan for the future, the consideration of future consequences, and overall life satisfaction. The sample consisted of 242 university students, with ages ranging from 16 to 31 (M = 18.5, SD = 1.7). Participants completed the New General Self-Efficacy Scale (NGSES), the Continuous Planning Scale (CPS), the Consideration of Future Consequences Scale (CFCS), and the Satisfaction with Life Scale (SWLS). Analyses demonstrated that all variables were significantly intercorrelated, with general self-efficacy being most strongly related to the SWLS, followed by the CFCS and the CPS. Implications are discussed.