The role of vision in the control of continuous multijoint movements

The authors investigated whether visual fixations during a continuous graphical task were related to arm endpoint kinematics, joint motions, or joint control. The pattern of visual fixations across various shapes and the relationship between temporal and spatial events of the moving limb and visual fixations were assessed. Participants (N=16) performed movements of varying shapes by rotating the shoulder and elbow joints in the transverse plane at a comfortable pace. Across shapes, eye movements consisted of a series of fixations, with the eyes leading the hand. Fixations were spatially related to modulation of joint motion and were temporally related to the portions of the movement where curvature was the highest. Gathering of information related to modulation of interactive torques arising from passive forces from movement of a linked system occurred when the velocity of the movement (a) was the lowest and (b) was ahead of the moving limb, suggesting that that information is used in a feedforward manner.     

Personality of Counselors and Administrators

The Sixteen Personality Factor Questionnaire was administered to 41 counselors and 41 administrators enrolled in graduate courses at Auburn University. The scores were compared in terms of individual factors and profiles. A discriminate analysis of scores correctly identified counselors in 31 out of 40 cases while principals were classified correctly in 34 out of 41 cases. Five factors found to be significantly different (P < .05) between counselors and administrators were: Factor C (Emotional vs Mature, Calm), Factor G (Expedient vs Conscientious), Factor I (Tough-Minded vs Tender-Minded), Factor L (Trusting vs Suspicious), and Factor N (Forthright vs Shrewd).     

Methods and findings in an analysis of a vocal operant

The relations among acoustic parameters of a vocal operant were considered and some methods for their measurement are described. Four human subjects (Ss) and one chick were employed in an experiment on the relations among vocal rate, vocal topography, and schedules of reinforcement. The earlier finding that schedules of reinforcement control human and infra-human vocal responding as they do other operants was replicated and extended to the case of variable-interval reinforcement. An analysis of response amplitude, pitch, and duration showed that the mean and variance of these parameters typically increase from CRF to VI, from VI to EXT and, for a second group of Ss, from CRF to EXT. The topography of the chick's vocal response appears to stand in the same relation to reinforcement operations as does the human vocal response.     

Developmental Features of Rapid Aiming Arm Movements Across the Lifespan

Using a lifespan approach, the authors investigated developmental features of the control of ballistic aiming arm movements by manipulating movement complexity, response uncertainty, and the use of precues. Four different age groups of participants (6- and 9-year-old boys and girls and 24- and 73-year- old men and women, 20 participants in each age group) performed 7 types of rapid aiming arm movements on the surface of a digitizer. Their movement characteristics such as movement velocity, normalized jerk, relative timing, movement linearity, and intersegment intervals were profiled. Analyses of variance with repeated measures were conducted on age and task effects in varying movement complexity (Study 1), response uncertainty (Study 2), and precue use (Study 3) conditions. Young children and senior adults had slower, more variant, less smooth, and less linear arm movements than older children and young adults. Increasing the number of movement segments resulted in slower and more variant responses. Movement accuracy demands or response uncertainty interacted with age so that the 6- and 74-year-old participants had poorer performances but responded similarly to the varying treatments. Even though older children and young adults had better performances than young children and senior adults, their arm movement performance declined when response uncertainty increased. The analyses suggested that young children's and senior adults' performances are poorer because less of their movement is under central control, and they therefore use on-line adjustments. In addition, older children and young adults use a valid precue more effectively to prepare for subsequent movements than do young children and senior adults, suggesting that older children and young adults are more capable of organizing motor responses than arc young children and senior adults.     

The Temporal Placement of Interpolated Movements in Short-Term Motor Memory,

Directional response biasing as a function of the recency of an interpolated act was examined on a lever device in a within-S design. The temporal occurrence of an interpolated act was systematically varied (5, 30, or 55 sec. after the criterion act) for three retention intervals (15, 40, and 65 sec.), and the location of the interpolated movement was held constant ± 40 deg. from the criterion position. Analysis of constant errors showed significant positive directional biasing for interpolated acts greater than criterion positions. Further analyses at the 40-and 65-sec. retention intervals supported a recency interpretation. As the retention interval increased, the positive constant error was maintained for interpolated acts with the same post-biasing interval, whereas constant error became increasingly negative as the post-biasing interval increased. Examination of variable error revealed a slight increase over time and no significant differences between directional conditions. The recency findings were discussed in terms of the view that reproduction of a criterion act is dependent on the relative decay states between the interpolated and criterion traces.     

Peer Difficulties in Children with Epilepsy: Association with Seizure,Neuropsychological, Academic,and Behavioral Variables

Purpose/Objective: A developmental psychopathology framework was used to examine variables associated with peer problems in children with epilepsy (CWE). Variables commonly associated with peer difficulties in typically developing children, such as inattentive behavior, anxious behavior, and academic achievement were investigated. Neuropsychological functioning, age at epilepsy onset, and seizure status were also examined.

Research Method/Design: Participants were 173 CWE, ages 8–15. Structural equation modeling (SEM) was used to determine which variables predicted peer problems in CWE and to test hypothesized interrelations among variables.

Results: The SEM revealed that anxious behavior mediated relations between neuropsychological functioning and peer difficulties and seizure status and peer difficulties. Inattentive behavior mediated the association between neuropsychological functioning and peer difficulties. Neuropsychological functioning mediated the relation between age at epilepsy onset and inattentive behavior, anxious behavior, and academic achievement.

Conclusions/Implications: As seen with typically developing children, inattentive and anxious behaviors are related to peer difficulties in CWE. Neuropsychological functioning, age at epilepsy onset, and seizure status are indirectly associated with peer difficulties; therefore, these variables are important to examine in CWE who are experiencing peer problems.     

Modulation of reflexive orienting to gaze direction by facial expressions

Facial expression and gaze perception are thought to share brain mechanisms but behavioural interactions, especially from gaze-cueing paradigms, are inconsistent. We conducted a series of gaze-cueing studies using dynamic facial cues to examine orienting across different emotional expression and task conditions, including face inversion. Across experiments, at a short stimulus–onset asynchrony (SOA) we observed both an expression effect (i.e., faster responses when the face was emotional versus neutral) and a cue validity effect (i.e., faster responses when the target was gazed-at), but no interaction between validity and emotion. Results from face inversion suggest that the emotion effect may have been due to both facial expression and stimulus motion. At longer SOAs, validity and emotion interacted such that cueing by emotional faces, fearful faces in particular, was enhanced relative to neutral faces. These results converge with a growing body of evidence that suggests that gaze and expression are initially processed independently and interact at later stages to direct attentional orienting.