Stimulus probability and prediction outcome as determinants of choice reaction time: Some procedural considerations

Effects of stimulus probability and prediction outcome on two-choice reaction speed (CRS) were determined when a frequency imbalance was reversed half-way through 300 samples of a 70/30 stimulus distribution and when the same 70/30 distribution was sampled for 1200 trials. Prior to each presentation Ss made a prediction; following each presentation Ss identified the stimulus by pressing a right-hand or left-hand trigger. CRS was faster to correctly predicted stimuli, and faster to the more probable stimulus. Ss who were informed of the frequency imbalance reacted significantly faster than Ss who were not. Both practice and boredom effects were demonstrated by using the extended number of trials. CRS was faster during the second session of 300 trials than during the first; after two sessions, CRS was slower during the second half of two additional sessions.     

Prediction outcome probabilities as determinants of choice reaction time

In a two-stimulus two-response choice reaction time (RT) task in which Ss made stimulus predictions, the probability of a correct prediction was manipulated between Ss. The magnitude of the difference in RT to correctly and incorrectly predicted stimuli (i.e., the prediction outcome effect) was an increasing function of the probability of a correct prediction This finding was primarily due to a reliable decrease in RT to correctly predicted stimuli as the probability of a correct prediction increased, since RT to incorrectly predicted stimuli was not affected by prediction outcome probability. These results were interpreted as partially supporting a continuous expectancy notion which involves facilitory and inhibitory mechanisms winch are differentially influenced by the probability of a correct prediction.     

A SELF-INSTRUCTIONAL PACKAGE FOR INCREASING ATTENDING BEHAVIOR IN EDUCABLE MENTALLY RETARDED CHILDREN

The purpose of this study was to develop a self-instructional package that would aid highly distractible retarded children in increasing their attending behavior in a training and two generalization (a one-to-one and a classroom) situations. Three untrained subjects were monitored for general comparison and social validation purposes. One of these control subjects was distractible and the other two (criterion comparison) were evaluated as not having attentional problems. A multiple baseline design was employed in which training was sequentially introduced across subjects. During training, the experimental subjects were taught through self-instruction to focus their attention and to cope with two tasks, math and printing. After learning the self-instructions the subjects were systematically and sequentially exposed to photo-slides of distracting situations, to audio-distractors composed of noisy lunchroom verbal peer interactions, and to in vivo distractors provided by kindergarten children playing with wooden blocks in the training setting. The entire training procedure was handled in a game-like context to maintain subject interest and to facilitate generalization. The results suggested that the training package produced direct and generalized changes in self-instructional behavior. In addition, a decrease in off-task behavior occurred during math, printing, and also during a phonics program in the one-to-one and classroom situations. However, reliable changes in academic task performance were not observed. Finally, no systematic changes on any of the dependent measures occurred for the three untrained subjects.     

Presence and television.

Film and a number of emerging entertainment technologies offer media consumers an illusion of nonmediation known as presence. To investigate the possibility that television can evoke presence, 65 undergraduate students were shown brief examples of rapid point‐of‐view movement from commercially available videotapes on a television with either a small screen (12 inches [30.5 cm], measured diagonally) or a large screen (46 inches [116.8 cm]). Participants' responses were measured via a questionnaire and a computer‐based recording of arousal (electrodermal activity). Viewers of both televisions reported an enjoyable sense of physical movement, excitement, involvement, and a sense of participation. Furthermore, as predicted, participants who watched the large screen television thought the movement in the scenes was faster, experienced a greater sense of physical movement, enjoyed the movement to a greater extent, found the viewing experience more exciting, and were more physiologically aroused. Practical and theoretical implications are discussed.     

Hemispheric asymmetry in the processing of high and low spatial frequencies: a facial recognition task

The research investigated the relationship between spatial frequency and visual field in a facial recognition task. Faces of neutral affect (Ekman, 1979) were tachistoscopically presented to the right or left visual field. The faces were presented alone, or masked with square wave gratings of 1, 24, or 48 cycles/degree, for a duration of 10 msec. Accuracy in recognizing each target face from a group of five served as the dependent measure. Subjects were 15 males and 15 females. ANOVA results included a frequency x visual field interaction effect (p less than .001). As was hypothesized, LVF errors were highest in the absence of low spatial frequencies, while RVF errors were highest when a higher range of spatial frequencies was removed. These results confirm that the hemispheres show a differential efficiency in processing high and low spatial frequency information in faces. They also offer empirical evidence to support the clinical findings that both hemispheres contribute to facial recognition.