Electrodermal measures of attention and effort to stimulus onset and offset for intramodal and intermodal tasks.

Two experiments were designed to assess the relationship between task difficulty and arousal. Electrodermal measures of tonic and phasic arousal to four levels of task difficulty at stimulus onset and offset were studied in college students for intramodal and intermodal tasks. The students were presented for 18 trails with visual-auditory or visual-visual stimuli with either 2.0-, 0.2-, or 0.02-sec difference between stimuli onset or offset, and asked to judge which stimulus came on or went off first or merely to observe the stimuli. Both frequency and amplitude of skin conductance responses reliably differentiated the levels of task difficulty for both the intramodal and the intermodal task. None of the measures of tonic level of arousal was reliable. Electrodermal measures of phasic responses accurately reflected the task demands.     

Personological dynamics of leadership

This study reports on the personality correlates of rated leadership using the California Psychological Inventory (CPI) and 50 college football players. Subjects were also given leadership scores using a CPI-based leadership regression equation. Two findings are of interest. First, consistent with past research, leaders were characterized by high scores on CPI Scales for Dominance, Self-Acceptance, and Responsibility. Second, coaches' leadership ratings correlated .62 with scores on the leadership regression equation. This provides an additional cross validation of this leadership equation and supports the notion that a stable set of personality traits characterize leaders. Some theoretical implications are discussed.     

Relations Between Contextual Performance,Personality, and Occupational Advancement

Two studies investigated relations between supervisors' evaluations of contextual performance and personality characteristics in jobs where opportunities for advance- ment were either absent or present. The first study examined performance in entry- level jobs where advancement, in general, was precluded; employees (N = 214) completed the Hogan Personality Inventory (HPI) as applicants and subsequently were rated by their supervisors for contextual performance. Results indicated that conscientiousness-measured by HPI Prudence scores-was significantly related to ratings of Work Dedication and Interpersonal Facilitation, which are dimensions of contextual performance. The results were corroborated in an independent sample. In the second study, employees (N = 288) in jobs with opportunities for advancement completed the HPI and their supervisors provided ratings for contextual performance. Results indicated that ambitiodsurgency-measured by HPI Ambition scores-pre- dicted contextual performance. These results also were confirmed in a second sample. Relations between personality and contextual performance are explained by the motives of cooperation-getting along-and status-getting ahead.     

Physiological correlates of intellectual function in children with sickle cell disease: hypoxaemia, hyperaemia and brain infarction

Lowered intelligence relative to controls is evident by mid-childhood in children with sickle cell disease. There is consensus that brain infarct contributes to this deficit, but the subtle lowering of IQ in children with normal MRI scans might be accounted for by chronic systemic complications leading to insufficient oxygen delivery to the brain. We investigated the relationship between daytime oxyhaemoglobin saturation (SpO2), cerebral blood flow velocity (CBFV) and intellectual function (IQ) using path-analysis in 30 adolescents with sickle cell disease (mean age 17.4 years, SD 4.2). Initial analyses revealed that the association between SpO2 and Full Scale IQ (FSIQ) was fully mediated by increased CBFV, whereby SpO2 was negatively correlated with CBFV and CBFV was negatively correlated with FSIQ, i.e. decreases in oxygen saturation are associated with increases in velocity, and increased velocity is associated with lowered IQ scores. The mediated relationship suggests that lowered IQ may be a function of abnormal oxygen delivery to the brain. Further analyses showed that the association between CBFV and IQ was significant for verbal but not for performance IQ. The pathophysiology characteristic of SCD can interfere with brain function and constrain intellectual development, even in the absence of an infarct. This supports the hypothesis that lowered intellectual function is partly explained by chronic hypoxia, and has wider implications for our understanding of SCD pathophysiology.     

Operant control of preening in pigeons

Preening in four pigeons was observed and recorded during operant level determinations, continuous and variable interval reinforcement, and extinction. The rate at which preening responses occur seems to be controlled by reinforcement in the same way as other operant behavior. Preening during VI reinforcement and extinction appeared to be similar to preening in many natural situations. With respect to the part of the body preened, considerable stereotypy of responding was shown by all birds, particularly during VI training; there was, however, a conspicuous absence of consistency in the development of stereotypy both within and between individual birds, perhaps due to the nature of the response.     

Generation of speech continua through monaural fusion

A procedure based on monaural fusion has been developed to construct acoustic continua between natural speech sounds, to be used in studies of speech perception. Two speech stimuli of similar temporal structure and different spectral composition are precisely aligned in time and presented simultaneously to the listener. By mixing both stimulus components in varying intensity ratios, a transition from one component to the other can be achieved. Such stimulus continua have several advantages over the synthetic continua commonly used in studies of categorical perception and related phenomena: They are based on real speech stimuli; the endpoint stimuli are unambiguous; and the stimuli are characterized by a well-defined physical variable, the relative intensity of the two components.