Consistency and error in motor performance

Two response measures that described the consistency and accuracy of motor performance were investigated. A pursuit tracking task was used as the vehicle whereby changes in perceptual motor performance could be monitored over several learning trials. The intra-individual variability of a subject's tracking response was compared to the root mean squared error that was accumulated during each block of trials. Whereas both response measures were sensitive to the changes in performance that occured as a result of practice, neither could be considered sufficiently informative as to be used as a sole indicator of skill acquisition. It appears that both consistency and error measures are needed to describe the subjects' performance as they acquire a perceptual motor skill.     

Second-order ‘fear’ conditioning in humans: Persistence of CR2 following extinction of CR1

Two groups of subjects were given pairings of a slide of a triangle (CS₁) with an aversive loud noise (US). After first-order conditioning a different figure (CS₂⁺) was paired with CS₁, whilst a third figure acted as a non-paired control (CS₂⁰). Conditioned second-order skin conductance responses (SCRs) were established to CS₂⁺ for all subjects who had undergone first-order conditioning. Following second-order conditioning, SCRs to CS₁ were extinguished and CS₂⁺ was subsequently tested for retention of its SCR evoking properties. For the group of subjects who believed they had an avoidance response available during the second-order conditioning phase, CR₂ failed to survive extinction of CR₁. However, for the group of subjects who had no perceived control over US presentation, extinction of cr₁ did not eliminate CR₂. This latter finding is consistent with associative analyses of second-order conditioning in animals and has clinical implications for the treatment of fear-related problems.     

Recognizing faces in and out of context

Two experiments are reported which examined the influence of context on face recognition accuracy for novel and familiar faces respectively. Context was manipulated by varying the physical background against which the faces appeared. In Experiment I, 80 student subjects observed 18 faces before attempting to recognize them in a sequence of 36 alternatives. For half the subjects, the backgrounds changed from study to test, while for the remainder they stayed the same. In addition, for half the subjects, both the pose and expression of the face also changed, while for the others it remained constant. Changes in pose plus expression and context significantly reduced recognition accuracy for the target faces. Experiment II used an identical design, except that the faces of celebrities replaced the novel faces. The influence of context was eliminated but the effects of pose and expression were maintained. However, when only faces which were actually identified by subjects were considered, the effects of pose and expression, too, were eliminated. The significance of these findings for theories of contextual memory are discussed.     

SUPPRESSION OF SELF-STIMULATION: THREE ALTERNATIVE STRATEGIES

Four boys with autistic-like behavior were treated for self-stimulatory behavior with three different treatment procedures—time-out, differential reinforcement of other behavior (DRO), and overcorrection. All four boys showed a rapid response to the overcorrection procedure. Three boys demonstrated some evidence of decrement in responding with time-out. During the DRO procedure, one showed a modest decrease, two showed no change, but one exhibited a consistent increase in responding under this condition. A multiple baseline applied to one of the subjects failed to reveal any generalization of suppression from one setting to another. A strong but not perfect relationship was found between a frequency and a duration measure of self-stimulation. There was some evidence of negative side effects for one boy during overcorrection and for another during time-out. None of these negative side effects was enduring. There was also some indirect evidence that overcorrection facilitated appropriate play.     

Conceptual preference for thematic or taxonomic relations: A nonmonotonic age trend from preschool to old age

Two experiments examined the development of conceptual preference for either thematic (functional) or taxonomic relationships in a match-to sample task. In Experiment 1 twenty subjects from each of five age groups—preschool to old age—completed a method of triads preference test where they were forced to choose a thematic or taxonomic match. Young and old individuals preferred the thematic parings while school age and college adults preferred the taxonomic matches. Although the Age × Preference relation was pronounced, the majority of subjects at all ages could provide adequate justification of both the preferred and nonpreferred relationship. In addition, kindergarten subjects in Experiment 2 could readily be trained to respond on the basis of the nonpreferred mode. These data suggest that the pervasive shift in conceptual responding from syntagmatic to paradigmatic, thematic to taxonomic, etc., represents a change in preference rather than a shift to a fundamentally new way of organizing knowledge.     

Increasing Career Center Accessibility for the Blind

To improve career planning services for visually impaired persons, the career center at Florida State University developed a self-directed program. This article describes strategies for making career information materials and resources more accessible to the blind.