Predicting and scaling hens' preferences for topographically different responses

Six hens were exposed to several concurrent (second-order) variable-interval schedules in which the response requirements on the alternatives were varied. The response requirements were one key peck versus five key pecks, one key peck versus one door push, and five key pecks versus one door push. Response- and time-allocation ratios undermatched the obtained reinforcement ratios but were well described by the generalized matching law. Time and response bias estimates from two pairs of response requirements were used to predict bias in the third pairing. The predicted values were close to those obtained; this result supports the notion that both numerically and topographically different responses act as constant sources of bias within the generalized matching law. The differences between the response and time biases could be accounted for by the different times needed to complete each response requirement. The results also suggest that the door push is a useful operant for research with domestic hens.     

Wishes, Motives, Goals, and Personal Memories: Relations of Measures of Human Motivation

ABSTRACT The purpose of this study was to compare measures of explicit and implicit motives. One hundred and one participants completed six measures of motivation, including Thematic Apperceptive stories, autobiographical memories, three wishes, personal striving lists, the Personality Research Form, and self-ratings. Stories, memories, wishes, and strivings were content-analyzed using Winter's (1989) system. Although overall correlations did emerge among explicit measures within the same motive, there were numerous correlations among methodologically similar measures of different motives. In general, explicit measures did not correlate with thematic measures of the same motives. Although correlations among measures were similar for men and women, explicit measures of power converged with thematic measures of power only for men. Exploratory factor analysis identified three factors: explicit achievement, explicit affiliation, and power. Implicit achievement motivation loaded negatively on the affiliation factor. Implications for research on implicit and self-attributed motivation are discussed.     

Life after Trauma: Personality and Daily Life Experiences of Traumatized People

In this study, we explored differences in personality and daily life experiences of traumatized (n= 26) versus nontraumatized (n= 30) college students. Study participants completed a variety of personality measures as well as a 28–day experience sampling study assessing daily activities, emotions, and physical health. Although not differing on general demographics, traumatized individuals reported more trait anxiety and lower self–esteem than nontraumatized individuals. They scored higher on Neuroticism, were more introverted, and were less emotionally stable than nontraumatized participants. Traumatized individuals also reported more cognitive disturbances, emotional blunting, and interpersonal withdrawal. They did not report being more depressed, but did endorse cognitive styles associated with heightened risk for depression. Earlier age of trauma was associated with more pathological outcomes: lower self–esteem and psychological well–being, more anxiety, more pessimism, and emotional constriction of positive mood. We compare this symptom profile to that of posttraumatic stress disorder.     

Are All Hostility Scales Alike? Factor Structure and Covariation Among Measures of Hostility1

Few studies have examined the correlational and structural relationships between measures of hostility that may predict coronary heart disease. Using data from a population-based study (N= 2,682), we examined the factor structure among the five subscales from Siegel's (1986) Multi-dimensional Anger Inventory, the three subscales from Spielberger et al.'s (1985) anger expression scales, a Cook-Medley (Cook & Madley, 1954) hostility subscale that measures cynicism, and items measuring hostility from four scales that assess Type A behavior. Eight separate factors were identified: hostile anger expression, perceived control over the expression of one's anger, frequency of anger, ease of anger provocation, brooding, hostile outlook, cynicism, and sullenness. These results suggest that the structure of hostility measures is more complex than previous factor analyses have suggested. Our findings point to the dangers in assuming that a factor structure can be generalized beyond the data on which it is based to provide theoretical statements about psychological structure. The new scales appear to be valid because they correlate with demographic variables and indicators of social support in the expected directions.     

Controlling the Ground Reaction Force During Lifting

The control of the ground reaction force vector relative to the center of gravity (CoG) was examined while subjects performed a back-lifting task. Six male subjects (aged 24.0 +/- 2.5 years) repeatedly lifted a barbell. A biomechanical analysis that used a linked segment model revealed that the summed rotations of body segments during lifting yielded a specific rate of change of the angular momentum of the entire body. This equaled the external moment provided by Fsubg; relative to CoG. This implies that multisegment movements involve control of the angular momentum of the entire body through an appropriately directed Fsubg;. Thus, in dynamic tasks Fsubg; is pointed away from rather than lined up with the CoG, as is the case in static tasks.     

Uncertainty in estimating distances from memory

Magnitude estimations involving spatial characteristics, such as distance, typically show a compressive function when estimates are made from memory. In particular, as the magnitude of a property grows larger and larger, estimates become more and more inaccurate, with increasing underestimates of the actual magnitude. Previous theories have attempted to explain this difference by supposing that magnitude estimation was accomplished through a reperceptual process, in which the errors of perception are magnified, or a transformation process, in which the memory trace undergoes a consistent alteration toward a more schematic form. The present experiments present evidence in support of an uncertainty hypothesis. When subjects are uncertain of the actual value of a distance, they are forced to guess on the basis of the mean distance they encountered, because they are unable to retrieve the information accurately. When they can retrieve the information, they are more certain and their estimates are more accurate. This hypothesis was also extended to integrative conditions in which the subjects were presented with the stimulus display in a piecemeal fashion. In these cases, distance estimates were derived by combining spatial representations. This method of presentation caused distance estimates to become less accurate.     

Subgroups of autistic children based on social behavior display distinct patterns of brain activity

Two questions were addressed in the present study: (1) Do autistic and normally developing children exhibit regionally specific differences in electroencephalographic (EEG) activity? (2) Do subgroups of autistic children classified according to Wing and Gould's (1979) system which emphasizes degree of social impairment exhibit distinct patterns of EEG activity? Twenty-eight children with autism (5 to 18 years of age) and two groups of normally developing children (one matched on chronological age and the other on receptive language level) participated. EEG was recorded from left and right frontal, temporal, and parietal regions during an alert baseline condition. Compared to normally developing children, autistic children exhibited reduced EEG power in the frontal and temporal regions, but not in the parietal region. Differences were more prominent in the left than the right hemisphere. Furthermore, subgroups of autistic children based on Wing and Gould's system displayed distinct patterns of brain activity. Compared to autistic children classified as “active-but-odd,” “passive” autistic children displayed reduced alpha EEG power in the frontal region.