Fourier analysis of movement patterns in pigeons

Fourier analysis describes the amount of variation in a time series by partitioning it into sinusoids of different amplitudes and wavelengths and quantifying the extent to which these waves are synchronized. The importance of a given wave is represented by its contribution to the explained variance of the time series. To illustrate its potential application to the study of movement, Fourier analysis was used to quantify the movement patterns of 2 pigeons on a variable-interval (VI) and a variable-time (VT) schedule of reinforcement. For comparison, the movements of 2 pigeons that did not receive reinforcement were similarly analyzed. Characteristic frequencies were higher during VI than during VT, and relatively low during nonreinforcement. We concluded that Fourier analysis can be used to represent movement patterns compactly, study their periodicity, stereotypy, and resonance, and assist in computer simulations and models of movement.     

The children of Mexican-American migrant workers: A population at risk?

The present study assessed intellectual, academic, and emotional strengths and weaknesses for a group of Mexican-American children of migrant farm workers. In order to test the vulnerability hypothesis, the test profiles of these children were contrasted with those of two groups of black children with similar demographic makeup. The children of one group (Clinical Black) had been referred previously for a psychological consultation while the children of the other (Nonreferred Black) had not. Across dependent measures, between-groups contrasts tended to describe the scores of the Migrant children as similar to those of the Clinical Black children and significantly below those of the Nonreferred Black children. The findings suggested specific intellectual, academic, and emotional vulnerabilities of the Migrant children and demonstrated the need to develop ameliorative programs for these children.The authors wish to thank the staff of C & Y, University of Virginia Hospital, especially Ms. Deborah Johnson and Ms. Suzanne Canale, whose cooperation and assistance made this project possible.     

Ambivalence in play and ritual

Life is not breath, but action; to live is to make use of our organs, our senses, our faculties, every part of ourselves which gives us the feeling of our own existence. Rousseau Emile     

A longitudinal analysis of personality structure and adolescent substance use

Within the context of a prospective longitudinal research design, the structure of personality and initial levels of drug use were used to predict, multivariately, later drug use among male and female adolescents. The findings indicated that personality and belief measures of nonconventionality provide a significant increment in the prediction of later drug use beyond a level achieved by knowing initial usage rates. In addition, other personality and belief measures yield further increments in the prediction of subsequent drug use. Developmentally, the results revealed a differentiation of drug use patterns across the year's time, with one pattern primarily reflecting alcohol use, and a second pattern primarily reflecting use of marijuana and ‘hard’ drugs. While both patterns were related to measures of nonconventionality, certain personality features distinguished between them. Emergent use of marijuana and ‘hard’ drugs was related to depression, mistrust and attractiveness, while emergent alcohol use was related to generosity, ambition, agility and cheerfulness. These results were cross-validated in two samples of subjects. Implications of the findings for adolescent psychosocial development are discussed.     

Selective migration— Still a viable hypothesis

Kamin (1980) has contended that arguments presented in Wolff (1979) are too weak to justify “resuscitating the selective migration debate.” Although Kamin's (1980) critique points up the need for closer scrutiny of the cumulative-deficit phenomenon, it fails to refute Wolff's (1979) conclusion that selective migration is partly responsible for the North-South black IQ differential.