Individual differences in the verbal coding of familiar visual stimuli

Two experiments were performed both of which involved the same-different comparison of pairs of alphabet letters. "Same" reaction times were obtained for both physical matches (e.g., AA) and name matches (e.g., aA). The results of both experiments supported the hypothesis that individual subjects would differ with respect to whether or not they based their physical matches on a comparison of verbal codes. In Experiment I, subjects differed in the size of their reaction time difference between physical and name matches, and in Experiment II, individuals differed with respect to whether or not the frequency of usage of the letters affected their reaction time for physical matches. In both experiments, the individual differences in verbally coding physical matches were related to Hock's (1973) individual differences distinction between subjects emphasizing analytic processes and subjects emphasizing structural processes.     

Comprehension and memory for pictures

The thesis advanced is that people remember nonsensical pictures much better if they comprehend what they are about. Two experiments supported this thesis. In the first, nonsensical "droodles" were studied by subjects with or without an accompanying verbal interpretation of the pictures. Free recall was much better for subjects receiving the interpretation during study. Also, a later recognition test showed that subjects receiving the interpretation rated as more similar to the original picture a distractor which was close to the prototype of the interpreted category. In Experiment II, subjects studied pairs of nonsensical pictures, with or without a linking interpretation provided. Subjects who heard a phrase identifying and interrelating the pictures of a pair showed greater associative recall and matching than subjects who received no interpretation. The results suggest that memory is aided whenever contextual cues arouse appropriate schemata into which the material to be learned can be fitted.     

The use of an untrained index response in a conditioned suppression paradigm

The need for extended training and motivational manipulations when using an instrumental index response in a conditioned suppression paradigm is often problematic. An index response requiring no prior training and no manipulation of motivational states is described. An experiment which exemplifies the use of this index response in a conditioned suppression paradigm is reported.     

Effect of different parameters of shock on tonic immobility

Four separate experiments were conducted with chickens to explore the effects of various parameters of electric shock on tonic immobility. Immobilizing subjects at varying times after the receipt of shock affected the duration of immobility only after delays of over 15 min. Duration of shock affected immobility differently, depending upon whether alternating current or continuous direct current was used. The effects of continuous dc, pulsating dc. and ac shock were also examined. The results were discussed in terms of shock onset-offset characteristics being an important consideration.     

Repeated vs varied distractors in immediate memory

Ss heard groups of eight spoken digits presented for immediate recall. Irrelevant distractor letters were interpolated between digits, using either the same letter interpolated eight times or eight different letters. The latter condition produced significantly more errors in recall. Error scores were also affected by rate of presentation of items and by whether letter-digit sequences started with a letter or a digit. It is suggested that selective immediate recall may bear some resemblance to aspects of visual search.     

The tonic immobility reaction in chickens: Response characteristics and methodology

A total of 379 chickens were run in five studies to assess the effect of different procedures on tonic immobility and to measure some of the response components of the reaction. The optimal period of manual restraint, by way of producing the most durable immobility response, was found to be 15 sec, and pretest holding conditions were shown to exert a significant influence on the reaction in naive birds. Birds who defecated during immobility or shortly after termination, remained immobile longer than comparable nondefecators. Duration of eye closure and latency of vocalization were also found to be good predictors of the duration of an immobility episode.     

A scalar product model for the multidimensional scaling of choice

A multidimensional scaling analysis is presented for replicated layouts of pairwise choice responses. In most applications the replicates will represent individuals who respond to all pairs in some set of objects. The replicates and the objects are scaled in a joint space by means of an inner product model which assigns weights to each of the dimensions of the space. Least squares estimates of the replicates' and objects' coordinates, and of unscalability parameters, are obtained through a manipulation of the error sum of squares for fitting the model. The solution involves the reduction of a three-way least squares problem to two subproblems, one trivial and the other solvable by classical least squares matrix factorization. The analytic technique is illustrated with political preference data and is contrasted with multidimensional unfolding in the domain of preferential choice.The present work was initiated at Oregon Research Institute under National Institute of Mental Health Grant MH 12972. It was reformulated and completed while the first author was a Visiting Research Fellow at Educational Testing Service.Presently at the Department of Mathematics, University of Toronto.