Stimulus intensity and information processing

The physiological and behavioral literature regarding effects of stimulus intensity on the time course of information processing is reviewed. The physiological data describe intensity effects on the sensory pathway. Reaction time studies show that the effect of intensity on behavioral responses also depends on and may be mediated by more cognitive processes. The degree to which intensity affects simple reaction time varies directly with the response criterion subjects use. The lack of this dependence in choice reaction time may indicate different intensity effects on energy and nonenergy pathways. The literature suggests that intensity affects the time course of information processing not only by influencing the speed of processing in sensory pathways, but also by affecting alertness and the time required to direct attention to a stimulus.     

Wavelength effects on simple reaction time

Simple reaction time was measured to spectral lights matched photometrically in luminance. When these lights were presented on a dimmer achromatic background, reaction time did not vary as a function of wavelength. Moreover, reaction times to white and chromatic lights were the same. When the luminance of the background was the same as that of the chromatic lights, reaction time increased and showed a strong effect of wavelength. Reaction time in this condition appeared to follow a saturation function. The results are described in terms of the operation of achromatic and chromatic processing channels.     

TRAINING FUNCTIONAL EXPRESSIVE LANGUAGE: THE ACQUISITION AND GENERALIZATION OF FIVE-ELEMENT SYNTACTIC RESPONSES1

A single-subject multiple-baseline design using within- and across-subject replication was employed to study the acquisition of expanded “agent-action-object” sentences and the spontaneous generation of this form in the natural environment. Three young language-delayed subjects were trained to describe various agent-action-object relationships with a five-element syntactical form. The language training strategy was a synthesis of the developmental-psycholinguistic and behavioral models. Dynamic interactions between familiar persons and objects were the stimulus events that the children mapped. A five-element syntactical form, previously absent from the children's language repertoires, was trained during individual sessions. Concurrent with baseline, training, and followup, each subject's language was monitored in another setting, the classroom during free play. After onset of training, the core elements of the complex syntactic form were spontaneously emitted by the child in its natural environment. The free-play data reflect individual differences in the emergence and frequency of each child's spontaneous use of the agent-action-object form. The acquisition and maintenance of the specific lexicon and syntax trained were tested by posttraining probes and responses to videotape presentations. These probes revealed generalization and maintenance of both the lexical and syntactical forms acquired in treatment. The main purpose of any language-training procedure should be to provide language that is functional for the child in the natural environment. This study, which documented the spontaneous usage of the core agent-action-object syntactical form in the natural environment, effectively trained a functional syntactical rule.     

An experimental analysis of impulsivity and impulse control in humans

In choosing between small, immediate and large, delayed reward, an organism behaves impulsively if it chooses the small reward and shows impulse control if it chooses the large reward. Work with nonhumans suggests that impulsivity and impulse control may be derived from gradients of delayed reinforcement. A model developed by Ainslie and by Rachlin suggests that preference for the rewards should be a function of when the choice is made: small reward with no delay may be preferred to large reward with delay X, but adding delay T to both alternatives should shift preference to the large reward. Three experiments investigated this preference reversal in humans, using termination of 90 dba white noise as the reinforcing event. Experiment 1 showed that under some instructional conditions 90-sec noise off with no delay was preferred over 120-sec noise off after a 60-sec delay, but that preference shifted to the large reward when a 15-sec delay (T) was added to both alternatives. Experiment 2 replicated this preference reversal under two conditions of large, delayed reward, and with three rather than two values of T. Experiment 3 confirmed this effect of T and showed that some humans committed themselves to the large reward when commitment could be made some time before presentation of the reward alternatives. These data support the Ainslie-Rachlin model and extend it to human choice behavior.     

The effects of cognitive style and training on performance ratings' validity

This study investigated how personal cognitive style and training effect rating validity with two different rating tasks. Male undergraduate volunteers (n = 53) served as raters and rated videotaped lecturers. Using the Embedded Figures Test to measure cognitive style, two groups of raters were formed: those who tend to structure information presented (articulated) and those who do not (global). Half of each cognitive style received observational training designed to be congruent with the behavioral rating task. All raters completed two rating tasks: one requiring an evaluative judgment and one requiring a judgment of behavior frequency. It was hypothesized that with the evaluative rating task, cognitive style would be and training would not be a significant predictor of validity, because the training was not relevant to the task. It was also hypothesized that with the observational task training would improve rating validity (overcoming cognitive style), because the training was relevant to the rating task. Both hypotheses were supported.I wish to thank Dr. Kevin Murphy for the use of the videotapes.