A note on sufficient conditions that a common factor will be determinate in an infinite domain of variables

It is proved for the common factor model withr common factors that under certain condition s which maintain the distinctiveness of each common factor a given common factor will be determinate if there exists an unlimited number of variables in the model each having an absolute correlation with the factor greater than some arbitrarily small positive quantity.The author is indebted to R. P. McDonald for suggesting the proof of Guttman's determinantal equation for the squared multiple correlation in predicting a factor from the observed variables used in the parenthetical note.     

Effects of food priming on instrumental acquisition and performance

Four experiments investigated the effects of a priming food reinforcement, given 0 or 75 sec pretrial, on runway performance of rats. The studies differed in the use of between-versus-within-subject designs, and by using food or water as the goal reinforcer. In Experiment 1, using food as the goal reward, subjects primed with food 0 sec pretrial conditioned slower than subjects primed 75 sec pretrial. In Experiment 2, using water as the goal reward, subjects primed with food 0 sec pretrial conditioned faster. These differences were evident on both prefed trials and on nonprefed test trials. Experiments 3 and 4 showed an opposite pattern of results when within-subject comparisons of 0- and 75-sec pretrial intervals were used: Food priming immediately pretrial facilitated food-rewarded running but inhibited water-rewarded running. The results suggest prefeeding has differential effects on acquisition and performance of instrumental behavior, and also depending upon the similarity of the priming and goal reinforcers.     

Conditioning functional enuresis: follow-up after retraining

Of 52 enuretics treated with bell-and-pad, 44 (84.6%) were initial successes. One year after training, 16 (30.8%) remained continually dry. Positive outcomes increased to 24 (46.2%) with the addition of successful retrainees and to 29 (55.8%), including 5 unretrained relapses who subsequently were found dry. Most clients reach initial success, but less than one third remain continually dry.

In retraining, over 84.2% (16/19) of the clients were again successful, but training time was shorter, and half relapsed a second time. Retraining is an appropriate and relatively easy approach for modifying relapse, at least for many enuretics. More rigorous assessment of retraining requires a balanced follow-up design and comparison with other approaches.     

Learning the invariants of a perceptual motor skill

The concept of invariant relative timing has typically been associated with the concept of a generalized motor programme. The present study approaches the phenomenon of invariant relative timing from the perspective of learning. The underlying question of concern for this study was, "What is learned." The specific question was whether relative timing is one of the essential properties of movement that is learned during skill acquisition. In the present experiment, subjects were given extensive practice in learning to track and reproduce a criterion waveform using a joystick control for their response. In order to test whether subjects learn the relative timing of a movement, they were transferred to tracking waveforms that were identical to the criterion in terms of relative timing, but different in terms of absolute timing. Measurements were taken on all waveforms in two conditions: (a) in a pursuit tracking condition where subjects were temporally constrained by the stimulus, and (b) in a reproduction condition where subjects' timing was not constrained. The outcome from both conditions gives support to the idea that humans learn invariant relative timing during the acquisition of a motor skill.     

Use of the family adaptability and cohesion evaluation scales in child clinical research

Although the FACES has become a widely used instrument for assessing children's family relations, the possible linearity vs. curvilinearity of its cohesion and adaptability scales has been treated inconsistently by investigators. This study evaluated whether samples of adolescent repeat offenders, young adult prisoners, and adolescent nonoffenders were discriminated better by a linear or curvilinear treatment of the FACES scores. Between-groups comparisons showed that significant effects were observed for each of the three curvilinear measures (cohesion-curvilinear, adaptability-curvilinear, distance-from-center) and only one of the two linear measures (cohesionlinear). These findings support the superiority of a curvilinear treatment of the FACES. In light of these findings, it is suggested that investigators who use FACES evaluate the linearity of the scales and determine whether a linear or curvilinear treatment of the data produces more meaningful results.