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.     

Cognitive factors in the concurrent differential conditioning of eyelid and skin conductance responses

The objectives of the study were to (1) determine if differential conditioning of eyelid responses ocurs only among subjects who accurately report knowledge of the CS-UCS relations, (2) assess whether differentially conditioned eyelid responding occurs only after the initial accurate interrial report, and (3) explore characteristics of differentially conditioned skin conductance responses (SCRs) obtained in an eyelid conditioning paradigm, with special attention to whether eyelid and SCR conditioning are similarly related to the subjects’ knowledge of the stimulus relations. Fifty-one male subjects were administered 80 differential eyelid conditioning trials, the CSs consisting of the 1,200-msec illumination of slides containing either grammatically correct or grammatically incorrect phrases. Significant differential SCR and eyelid conditioning was obtained for both V- and C-form eyelid responders, but only for subjects who accurately reported the CS-UCS relations. The initial appearance of SCR and eyelid differentiation was related within the trial sequence to subjects’ recognition of the stimulus relations. Eyelid and SCR conditioning were related similarly to knowledge of the stimulus relations, the exception being that subjects who recognized the stimulus relations late in the trial sequence did not develop reliable eyelid differentiation.     

An alternative to grapheme-phoneme conversion rules?

When orthographic factors were tightly controlled in a lexical decision task, it was observed that orthographic similarity rather than homophony with a word led to increased reaction times to nonwords. This result suggested that the pseudohomophone effect is not a phonological effect. Instead, a conversion of the graphemes of a stimulus item into different graphemes via a set of grapheme-grapheme conversion rules was supported. When phonological factors were tightly controlled and orthographic similarity varied, evidence for the existence of grapheme-grapheme rules was provided in both a lexical decision task and a task in which subjects were required to say whether an item was pronounced in the same way as a word. Even in the latter task, in which the likelihood of phonological recoding was optimized, it appeared that grapheme-phoneme rules were rarely, if ever, used.     

A microcomputer-controlled complex reaction time instrument

An inexpensive microcomputer system that measures complex reaction time to a visual stimulus is described. This system can determine the rate of gain of information by utilizing a two-, four-, or eight-choice reaction time task encompassed within the same unit. The system turns on randomly chosen lights and monitors the time required for the subject to depress a corresponding switch. Information describing the stimulus and the subject’s response are printed on a Teletype after each response.     

A contextual effect in feature detection with application of signal detection methodology

These experiments address the question of whether the perception of a form is exclusively determined by a prior analysis of its elements. Employing a signal detection task, Experiment 1 replicated the finding of Weisstein and Harris (1974) that embedding a line segment feature in a unitary figural context facilitates its detection. The results of Experiment 2 suggest that the most probable agent of this context effect on feature detection is the three-dimensionality of the unitary context. With bi-hemiretinal stimulus presentation. Experiment 3 showed a significant context effect in the right, but not in the left visual field. Some current paradigms are applied to these results.     

EVALUATING TREATMENT CHALLENGES WITH DIFFERENTIAL REINFORCEMENT OF ALTERNATIVE BEHAVIOR

In prior research, differential reinforcement of alternative behavior (DRA) has been implemented at optimal treatment values: Problem behavior is never reinforced, and alternative behavior is always reinforced. However, in application, DRA is unlikely to be conducted optimally. In this study, following a functional analysis phase and a differential reinforcement at full implementation phase, we challenged initially positive treatment effects for 3 participants by implementing DRA at less than optimal parameters. For example, some occurrences of problem behavior were reinforced, and some occurrences of alternative behavior were not reinforced. Results suggested that when exposed to DRA at full implementation, participants showed a bias toward appropriate behavior in subsequent conditions during which “mistakes” (treatment challenges) were intentionally introduced. In addition, the negative effects of treatment challenges were quickly reversible, in comparison to the positive effects of DRA, which were not quickly reversible in the face of treatment challenges.     

The role of planning for intention-behavior consistency

Two studies investigated how planning affects intention-behavior consistency. In Study 1 an experimental group and control group which each consisted of 14 undergraduates were requested in computerized interviews to indicate which activities they intended to perform on the following day. Subjects in the experimental group were also requested in a second phase of the interviews to specify when and where they intended to perform the activities. The results showed that activities for which time and place had been specified were more likely to be performed. In Study 2 another 75 undergraduates volunteered to participate in an experiment in which they were requested to perform an activity (reporting mood effects of reading a prose excerpt) by themselves on one of three following days. One group of subjects only agreed to perform the activity, another group agreed to perform the activity as well as indicated when and where they would do it, and a third group in addition to this indicated which other activities they would perform on the same day. In support of the hypothesis that planning an activity increases the likelihood that it will be performed, the results showed that subjects who indicated other activities more frequently performed the target activity. More efficient time management resulting from planning may account for the findings, although further research is needed to show this conclusively.