Effects of d-amphetamine and pentobarbital under concurrent fixed-ratio schedules.

Pigeons were studied under a two-key concurrent fixed-ratio schedule of food presentation. During the first five sessions, the fixed-ratio requirements were 30 responses on one key (major key) and 120 responses on the other key (minor key): responding occurred almost exclusively on the major key. When the fixed-ratio requirements were then made equal at 30 responses on both keys, responding continued to predominate on the major key. The asymmetric distribution of responses persisted when the concurrent fixed-ratio fixed-ratio schedule was interrupted with periods during which the major key was associated with extinction while the other key remained associated with a fixed-ratio schedule. Additionally, in some subjects the fixed-ratio requirements were increased. These schedule modifications decreased the asymmetry in responding but did not eliminate it. d-Amphetamine decreased rates on both keys and slightly increased the asymmetric distribution of responses, while pentobarbital reversed the distribution of responses by increasing low rates and decreasing high rates. The pigeons maintained their original asymmetric distribution of responses during the 1 1/2-year-long study, despite schedule alterations and drug administrations.     

Temporal discrimination and a free-operant psychophysical procedure.

Pigeons were presented a series of keylight time periods (separated by blackouts) during which two response keys were lit, one by blue light and the other either by orange or green. Blue-key responses changed the color on the other key. Orange-key responses sometimes produced food during the first half of a time period; green-key responses sometimes produced food during the second half. In three experiments, the probability of a green-key response increased as a function of elapsed time. Experiment 1 compared performance when the duration of the keylight periods was varied across a wide range. Discrimination of performance was similar across the range of durations. Experiment 2 varied both relative reinforcement rate and the local reinforcement rate for orange-key and green-key responses. These manipulations produced changes in response bias but not discrimination sensitivity. Experiment 3 varied the local temporal placement of reinforcers within time periods and demonstrated that choice behavior was affected by differential reinforcement at different points during the time periods. The results were consistent with previous research on duration discrimination that used psychophysical trials procedures.     

USING INTERMITTENT REINFORCEMENT TO PROGRAM MAINTENANCE OF VERBAL/NONVERBAL CORRESPONDENCE

We investigated the effects of an intermittent reinforcement procedure on maintenance of verbal/nonverbal correspondence with nutritious snack choices in a day-care setting. Nutritious snack choices were first established using correspondence training procedures in a multiple baseline across three children. Withdrawal of the procedures with one subject led to loss of appropriate responding, suggesting the need for a maintenance strategy. The intermittent reinforcement procedure was implemented in a multiple baseline across subjects. Nutritious snack choices were observed consistently during the intermittent reinforcement condition and the subsequent extinction condition.     

A NEUROBIOLOGICAL NON ALTERNATIVE: REJOINDER TO LEWIS,BAUMEISTER, AND MAILMAN

Certain misrepresentations of our theory of self-stimulatory behavior by Lewis, Baumeister, and Mailman (1987) are corrected and several questions raised by the commentators are answered. Their proposed neurobiological alternative is considered briefly and judged to be insufficiently detailed, inadequate in scope, and therefore premature.     

RESPONSE INTERRUPTION AND DRL FOR THE REDUCTION OF RAPID EATING

We assessed the efficacy of several procedures for reducing the rate of eating responses during mealtime by three institutionalized mentally retarded clients. A time-based (15 s) response interruption procedure was implemented which resulted in little change in eating responses for 2 of 3 subjects. A spaced-responding DRL 15-s procedure resulted in decreases in eating responses to target levels only after a prompting procedure was added. Procedures were evaluated using a multiple baseline across subjects design with assessment of generalization to nontreated meals. A change in eating behavior during breakfast occurred only after direct training in the breakfast setting. Maintenance data were collected at 1- and 5-month follow-up periods.     

Classification of concatenation measurement structures according to scale type

A relational structure is said to be of scale type (M,N) iff M is the largest degree of homogeneity and N the least degree of uniqueness (Narens, 1981a, Narens, 1981b) of its automorphism group.Roberts (in Proceedings of the first Hoboken Symposium on graph theory, New York: Wiley, 1984; in Proceedings of the fifth international conference on graph theory and its applications, New York: Wiley, 1984) has shown that such a structure on the reals is either ordinal or M is less than the order of at least one defining relation (Theorem 1.2). A scheme for characterizing N is outlined in Theorem 1.3. The remainder of the paper studies the scale type of concatenation structures 〈X, ?, ° 〉, where ? is a total ordering and ° is a monotonic operation. Section 2 establishes that for concatenation structures with M>0 and N<∞ the only scale types are (1,1), (1,2), and (2,2), and the structures for the last two are always idempotent. Section 3 is concerned with such structures on the real numbers (i.e., candidates for representations), and it uses general results of Narens for real relational structures of scale type (M, M) (Theorem 3.1) and of Alper (Journal of Mathematical Psychology, 1985, 29, 73–81) for scale type (1, 2) (Theorem 3.2). For M>0, concatenation structures are all isomorphic to numerical ones for which the operation can be written $\text{x°y = yf(}\text{x}\text{y}\text{)}$, where f is strictly increasing and $\text{f(x)}\text{x}$ is strictly decreasing (unit structures). The equation f(x^?)=f(x)^? is satisfied for all x as follows: for and only for ? = 1 in the (1,1) case; for and only for ?=kⁿ, k > 0 fixed, and n ranging over the integers, in the (1, 2) case; and for all ?>0 in the (2, 2) case (Theorems 3.9, 3.12, and 3.13). Section 4 examines relations between concatenation catenation and conjoint structures, including the operation induced on one component by the ordering of a conjoint structure and the concept of an operation on one component being distributive in a conjoint structure. The results, which are mainly of interest in proving other results, are mostly formulated in terms of the set of right translations of the induced operation. In Section 5 we consider the existence of representations of concatenation structures. The case of positive ones was dealt with earlier (Narens & Luce (Journal of Pure & Applied Algebra27, 1983, 197–233). For idempotent ones, closure, density, solvability, and Archimedean are shown to be sufficient (Theorem 5.1). The rest of the section is concerned with incomplete results having to do with the representation of cases with M>0. A variety of special conditions, many suggested by the conjoint equivalent of a concatenation structure, are studied in Section 6. The major result (Theorem 6.4) is that most of these concepts are equivalent to bisymmetry for idempotent structures that are closed, dense, solvable, and Dedekind complete. This result is important in Section 7, which is devoted to a general theory of scale type (2, 2) for the utility of gambles. The representation is a generalization of the usual SEU model which embodies a distinctly bounded form of rationality; by the results of Section 6 it reduces to the fully rational SEU model when rationality is extended beyond the simplest equivalences. Theorem 7.3 establishes that under plausible smoothness conditions, the ratio scale case does not introduce anything different from the (2, 2) case. It is shown that this theory is closely related to, but somewhat more general, than Kahneman and Tversky's (Econometrica47, 1979, 263–291) prospect theory.     

Reanalysis of the equation for simple action

De Villiers and Herrnstein (1976) have shown that the equation for simple action, derived from the matching law, predicts change in behavioral output for some 40 experiments in which the value of a single source of reinforcement has been varied. Using only the positive-reinforcement studies they cite that used five or more different reinforcement values, we found the high percentage of variance they report accommodated by this equation (94%) is predicated on instances of averaging rates of behavioral output before making a least-squares fit of the equation. In our reanalysis, which minimizes rate averaging, only 78% of the data variance is accommodated. This diminished data-variance accommodation can be improved by adding parameters that permit the equation's scaling constant to change as a function of reinforcement. Although these parameters permit acceptable levels of accommodation of data variance, they correspond to no obvious psychological processes. These findings support the view that the equation for simple action is an inadequate model for behavioral output.     

OPIOID ABSTINENCE REINFORCEMENT DELAYS HEROIN LAPSE DURING BUPRENORPHINE DOSE TAPERING

A positive reinforcement contingency increased opioid abstinence during outpatient dose tapering (4, 2, then 0 mg/day during Weeks 1 through 3) in non‐treatment‐seeking heroin‐dependent volunteers who had been maintained on buprenorphine (8 mg/day) during an inpatient research protocol. The control group (n = 12) received $4.00 for completing assessments at each thrice‐weekly visit during dose tapering; 10 of 12 lapsed to heroin use 1 day after discharge. The abstinence reinforcement group (n = 10) received $30.00 for each consecutive opioid‐free urine sample; this significantly delayed heroin lapse (median, 15 days).     

Shy teens and their peers: Shyness in respect to basic personality traits and social relations

The main purpose of this paper was to examine shyness in teenagers from two perspectives: in terms of its relations with basic personality traits and in terms of its influence on the processes that occur in the social networks of high school students. First, we found that shyness was negatively predicted by extraversion and positively by neuroticism. Second, using exponential random graph models we demonstrated that shyness across network effects was similar to reversed extraversion (introversion): Both negatively predicted the number of outgoing relations, whereas they did not affect the number of incoming relations. We discuss the issue of locating shyness in the space of personality traits, supporting the relevance of ascribing it to introversion.     

“Leave Your Comment Below”: Can Biased Online Comments Influence Our Own Prejudicial Attitudes and Behaviors?

Increased use of online communication in everyday life presents a growing need to understand how people are influenced by others in such settings. In this study, online comments established social norms that directly influenced readers' expressions of prejudice both consciously and unconsciously. Participants read an online article and were then exposed to antiprejudiced or prejudiced comments allegedly posted by other users. Results revealed that exposure to prejudiced (relative to antiprejudiced) comments influenced respondents to post more prejudiced comments themselves. In addition, these effects generalized to participants' unconscious and conscious attitudes toward the target group once offline. These findings suggest that simple exposure to social information can impact our attitudes and behavior, suggesting potential avenues for social change in online environments.