Discrimination of methadone and cocaine by pigeons without explicit discrimination training.

Pigeons were trained to peck a key on a variable-interval 2-min schedule of food reinforcement. Prior to each session, either 2.0 mg/kg methadone (n = 3), 3.0 mg/kg cocaine (n = 4), or 5.6 mg/kg cocaine (n = 2) was administered. When each pigeon's rate of pecking was stable, a range of doses of the training drug and saline were administered prior to 20-min extinction sessions separated by at least four training sessions. Rate of pecking during these extinction tests was generally an increasing function of dose, with the lowest rates obtained following saline and low doses and the highest rates obtained following doses near the training doses. Dose functions from pigeons trained with 5.6 mg/kg cocaine were steeper than those from pigeons trained with 3.0 mg/kg cocaine. Pigeons trained with methadone or 3.0 mg/kg cocaine were then given discrimination training, in which food reinforcement followed drug administration and 20-min extinction sessions followed saline administration. Rates of pecking under these conditions quickly diverged until near-zero rates were obtained following saline and high rates were obtained following drug. Discrimination training steepened dose functions for the training drugs, and the effects of several other substituted drugs depended on the pharmacology of the training drug. The pigeons trained with 5.6 mg/kg cocaine were tested with d-amphetamine, methadone, and morphine prior to discrimination training. d-Amphetamine increased rates dose dependently, and methadone and morphine did not. The results suggest that discriminative control by methadone and cocaine was established without explicit discrimination training.     

The relationship between childhood violence and alcohol problems among men who batter: An empirical review and synthesis

The available literature indicates that: (a) experiences of childhood violence are associated with mediator variables, including antisocial behaviors and depressive symptomatology, that are themselves associated with development of alcohol problems and perpetration of partner violence for men in adulthood; (b) experiences of childhood violence and, more strongly, observation of interparental violence during childhood predict perpetration of partner violence in adulthood for males; (c) presence of partner violence is associated with certain types of alcohol problems for men; and (d) both partner violence and alcohol problems are associated with marital conflict. However, available research has often excluded important moderator variables, such as history of familial and parental alcohol problems and history of parental psychiatric disorders. Based on the available research, two indirect pathways between childhood violence and adulthood problems (i.e., alcohol problems and partner violence) are proposed as guides for future research in the areas of family violence and alcohol problems for men. Further, bidirectional associations between alcohol problems and partner violence are proposed. Finally, inclusion of important moderator and mediator variables in multivariate research designs is suggested.     

The sampling distribution ofd′

The distribution of sample $\hat d's$ , although mathematically intractable, can be tabulated readily by computer. Such tabulations reveal a number of interesting properties of this distribution, including: (1) sample $\hat d's$ are biased, with an expected value that can be higher or lower than the true value, depending on the sample size, the true value itself, and the convention adopted for handling cases in which the sample $\hat d'$ is undefined; (2) the variance of $\hat d'$ also depends on the convention adopted for handling cases in which the sample $\hat d'$ is undefined and is in some cases poorly approximated by the standard approximation formula, (3) the standard formula for a confidence interval for $\hat d'$ is quite accurate with at least 50–100 trials per condition, but more accurate intervals can be obtained by direct computation with smaller samples.     

The psychologist's role in assessing and facilitating patients' knowledge of advance directives in medical settings: A preliminary investigation

In a time of budgetary shortfalls in the medical industry, an aging population, and an increased emphasis on health care choices, psychologists are being called upon to administer advance medical directive programs to patients. This study reports preliminary findings from a program to assess and facilitate patients' knowledge of advance directives (ADs) by the Psychology Service at the Ann Arbor VA Medical Center. The participant pool included 243 male veteran patients admitted to medical and surgical wards at the hospital. The intervention included the use of a computer-generated prompt for consultation, which was sent to the psychology staff in response to a patient inquiry regarding ADs. It also involved an increased emphasis on the delivery of written material on ADs by the admissions clerks. The intervention appeared to result in a modest increase in patients' knowledge of advance directives. Suggestions are offered for areas that should be emphasized in future attempts to increase patients' knowledge and utilization of advance directives.     

Semantic facilitation and lexical access during sentence processing

An experiment was conducted testing predictions derived from context-dependent and context-independent models of lexical access. Four types of unambiguous test sentences were constructed. The direct object of each test sentence was preceded by a verb that was either semantically related or unrelated to it, and by an adjective that was semantically related or unrelated. Context-dependent models predict that the speed with which the object noun is retrieved from the mental lexicon will be faster when the verb and/or the adjective is semantically related; context-independent models predict no such facilitation. Forty-four subjects each heard 32 test sentences and were asked to monitor within the sentence for a word-initial target phoneme. The target phoneme occurred on the word following the object noun. Reaction times to detect the targets were obtained. According to context-dependent models, these times should be shorter when related words precede the object noun, and that is what was found. It was also observed that the facilitation effects due to the related verbs and adjectives were additive. Implications of these results were discussed.     

Multidimensional same--different judgments: evidence against independent comparisons of dimensions

Commonly discussed models of performance in the multidimensional same-different task are based on the assumption that independent same-different decisions are reached for each of the stimulus dimensions used in an experiment. In these models, a higher level mechanism examines th outcome of these independent decisions in order to determine whether the stimuli are the same or different overall. Previous evidence indicating that these models are inconsistent with results from same trials is summarized, and a new test of the above assumption using data from different trials is proposed. Detailed analysis of reaction times from different trials is shown, at least for some pairs of dimensions, to be incompatible with the view that separate same-different decisions are reached for each dimension. The major finding is that there are more relatively fast responses in a condition with two dimensions different, compared with the two conditions with only one of the dimensions different, than any processing model treating the dimensions separately could predict. The results suggest that partial information may be combined across dimensions in order to reach a "different" judgment.     

The effect of set size on hemifield asymmetries in letter recognition

Single letters were presented tachistoscopically in the left or right hemifield to right-handed observers. Superior recognition of letters on the right was found for letters chosen from subsets containing four items, but no differences were found when any letter, or any symmetrical letter, could appear. In a second experiment, the right hemifield advantage was found under conditions requiring the subject to determine the subset only when the subset chosen was appropriate. Results were discussed in terms of the adequacy of language-based explanations of hemifield asymmetries in letter recognition.