Optimal sequences of trials for balancing practice and repetition effects

This paper describes procedures for generating trial sequences to balance out practice effects and intertrial repetition effects in experiments consisting of repeated trials. In the sequences presented, each stimulus appears an equal number of times, is preceded equally often by itself and by each other stimulus, and is distributed in a “balanced” manner throughout the block of trials. Two criteria for balance are employed. One criterion aims to equalize the average position of each stimulus in the sequence. The second criterion maintains, as much as possible, a uniform interval between appearances of each stimulus in the sequence. For each criterion, optimal or near-optimal sequences are presented for experiments involving from three to nine different stimulus conditions. Suggestions are included for extending (e.g., doubling or tripling) the length of the sequences.     

INCREASING INDICES OF HAPPINESS AMONG PEOPLE WITH PROFOUND MULTIPLE DISABILITIES: A PROGRAM REPLICATION AND COMPONENT ANALYSIS

We replicated a program to increase indices of happiness among people with profound multiple disabilities and conducted a component analysis of the program. The program involved presentation and contingent withdrawal of stimuli that had been identified as preferred based on preference assessments and staff opinion. The program was implemented with 3 adult students and was accompanied by increased happiness indices for each student. Subsequent implementation of the two types of stimuli indicated that preferred stimuli based on preference assessments were more consistently accompanied by increased happiness indices than were preferred stimuli based on staff opinion. Social validity measures supported the definition of happiness, in that raters' subjective opinions of the students' happiness coincided with the observed happiness indices. Results are discussed regarding the importance and practical implications of using preference assessments for determining stimuli for increasing happiness indices. Future research areas are suggested, focusing on increasing happiness and other quality-of-life indicators during the daily routines of people with profound disabilities.     

The Possible-Word Constraint in the Segmentation of Continuous Speech

We propose that word recognition in continuous speech is subject to constraints on what may constitute a viable word of the language. This Possible-Word Constraint (PWC) reduces activation of candidate words if their recognition would imply word status for adjacent input which could not be a word - for instance, a single consonant. In two word-spotting experiments, listeners found it much harder to detectapple,for example, infapple(where [f] alone would be an impossible word), than invuffapple(wherevuffcould be a word of English). We demonstrate that the PWC can readily be implemented in a competition-based model of continuous speech recognition, as a constraint on the process of competition between candidate words; where a stretch of speech between a candidate word and a (known or likely) word boundary is not a possible word, activation of the candidate word is reduced. This implementation accurately simulates both the present results and data from a range of earlier studies of speech segmentation.     

Effects of Alprazolam on Complex Human Functioning1

Benzodiazepines can reduce anxiety, can have favorable effects upon sleep, and may diminish problems that interfere with patients' quality of life. On the other hand, these drugs can generate transient anterograde amnesia and may diminish aspects of task performance. Research on the impact of alprazolam and other “tranquilizing” drugs has generally focused on tasks that remain below the complex efforts of managerial or professional personnel. Alprazolam-induced reduction of anxiety under challenging conditions might aid complex task performance, yet anterograde amnesia might interfere. In the present research, managers participated in validated complex simulation tasks. In a double-blind, dual crossover design, placebo, 0.5 mg, or 1.0 mg alprazolam was administered on 2 occasions during the task day. Drug treatment diminished performance on measures that require sequential actions but improved performance on measures less subject to short term memory but more determined by long-term style of functioning. Thus, depending on task requirements, positive or negative alteration of performance might occur.     

Cross-Cultural Testing of Three Social Cognitive Theories: An Application to Condom Use1

The aim of this study was to test the cross-cultural validity of Fishbein and Ajzen's theory of reasoned action, Ajzen's theory of planned behavior, and Triandis' theory of interpersonal behavior and to apply them to understanding the intention to use a condom with a new partner in three ethnocultural communities: Latin American, English-speaking Caribbean, and South Asian. All respondents were recruited from multiple ethnocultural-venues using predetermined sampling frames and quotas for each community. The results indicated that the three theories have cross-cultural validity, but the theories of Ajzen and Triandis performed better than the theory of Fishbein and Ajzen. It is recommended that role beliefs and moral norm (personal normative belief) be added to Ajzen's model to maximize its predictive and explanatory ability.     

Self-reported levels of psychopathology of drug abusers not currently in treatment

This study assessed levels of psychopathology, as measured by the Symptom Checklist-90-Revised, of drug users not in treatment. These levels were then compared with levels of psychopathology reported previously in the literature of drug users in treatment, the general population, psychiatric inpatients, and psychiatric outpatients. Results suggest that drug users not in treatment endorse significantly lower levels of psychopathology than drug users in treatment, psychiatric inpatients, and psychiatric outpatients. However, they endorse significantly higher levels of pathology than adult nonpatients and they appear most similar to adolescent nonpatients. Implications for clinical work (prevention and intervention) as well as for future research are discussed. The study also established preliminary cultural validity of SCL-90-R with Alaska Natives.     

Speeded detection of vowels: A cross-linguistic study

In four experiments, listeners’ response times to detect vowel targets in spoken input were measured. The first three experiments were conducted in English. In two, one using real words and the other, nonwords, detection accuracy was low, targets in initial syllables were detected more slowly than targets in final syllables, and both response time and missed-response rate were inversely correlated with vowel duration. In a third experiment, the speech context for some subjects included all English vowels, while for others, only five relatively distinct vowels occurred. This manipulation had essentially no effect, and the same response pattern was again observed. A fourth experiment, conducted in Spanish, replicated the results in the first three experiments, except that miss rate was here unrelated to vowel duration. We propose that listeners’ responses to vowel targets in naturally spoken input are effectively cautious, reflecting realistic appreciation of vowel variability in natural context.     

The partial punishment effect following minimal acquisition training: Sodium amobarbital and the stimulus properties of early punished trials

In a runway investigation, six groups of rats received limited runway training such that partial punishment, partial reinforcement, or continuous reinforcement was accompanied by sodium amobarbital or saline. Following an interpolated phase of continuous reinforcement without injections, all groups were given punished extinction. The entire experiment was conducted under widely spaced conditions (ITI = 24 hr). It was found that partial punishment increased resistance to punished extinction relative to partially and continuously reinforced controls when acquisition was given under saline. When partial punishment training was accompanied by amobarbital this effect was eliminated. The drug was observed to have no effect on the punished extinction performance of the partial reinforcement and continuous groups, respectively. Moreover, the partial reinforcement effect (PRE) did not generalize to punished extinction. These data provide information concerning the difference between the stimuli associated with the early trials of punishment and nonreward and indicate that the former but not the latter contain emotional elements.