Pigeons' preference for free choice: number of keys versus key area.

In concurrent-chains schedules, pigeons prefer terminal links that provide two keys correlated with reinforcers (free choice) over those that provide only one key (forced choice), terminal-link reinforcement rates being equal. With same-size keys, free choice provides a larger area available for pecking. Preferences were examined using terminal links that differed in key number only (one or two) or key size only (small and medium or medium and large), or that equated the area of the two free-choice keys with that of the forced-choice key. Medium (standard) keys were typically preferred to small keys, but indifference was typically obtained between medium and large keys. The size preference usually overrode free-choice preference with one medium key pitted against two small keys, but free-choice preference was reliably observed with one large key pitted against two medium keys. In other words, preferences were a joint function of key number and key area, implying that free-choice preference is not reducible to preference for larger key areas. Free-choice preference requires separate keys rather than larger areas; the relevant behavioral units are the discriminated operants correlated with each terminal-link key rather than classes defined by topographical features such as area or perimeter.     

Schema anticipation in recall: memory process or report strategy?

Summary This article reports an experimental investigation testing the hypothesis that recall reports are systematically biased by the recaller's knowledge about who is to receive the recall report, while that bias is absent from a recognition test. Subjects listened to one of two versions of a story recounting John's visit to the doctor. After the story was read, subjects were asked to recall the story either with standard-recall instructions or with instructions to recall for peers, for Martians, or for a contest. In a fifth condition, subjects performed a filler activity, viz., the recall of a personal experience. After the recall test subjects were administered a recognition test. Between the groups no systematic differences in memory performance were observed in the recognition test. Recall for peers appeared to be poorer than recall in the other conditions. Subjects in the recall for a contest condition scored higher than the subjects in the other groups. Not only did groups differ with respect to bias, but there were also systematic differences in the memory or discrimination scores. The findings are discussed within the framework of schema theory.     

Discrimination theory of rule-governed behavior

In rule-governed behavior, previously established elementary discriminations are combined in complex instructions and thus result in complex behavior. Discriminative combining and recombining of responses produce behavior with characteristics differing from those of behavior that is established through the effects of its direct consequences. For example, responding in instructed discrimination may be occasioned by discriminative stimuli that are temporally and situationally removed from the circumstances under which the discrimination is instructed. The present account illustrates properties of rule-governed behavior with examples from research in instructional control and imitation learning. Units of instructed behavior, circumstances controlling compliance with instructions, and rule-governed problem solving are considered.     

Semantic operations deficits in sentence comprehension

Summary The ability of aphasic patients to comprehend sentences involving the combination of two linguistic operations was tested in a sentence/picture matching task. Sentences included affirmative, negative, uncompared and comparative types. Aphasic patients had significantly greater difficulty in understanding negative-comparative constructions than sentence types involving only a single operation. Comparison of the responses of the aphasic patients with data obtained in a perceptual comparison task revealed that a subgroup of patients had marked difficulty in integrating information in both tasks. The results are interpreted as an indication that some aphasic patients are especially disturbed in their ability to combine several operations in the construction of semantic representations for sentences. It is further argued that this deficit may extend to an inability to integrate information in the perceptual/spatial domain, as suggested by Luria in his discussion of the syndrome of semantic aphasia.The research reported here was supported by NIH research grant 14099 to The Johns Hopkins University. We would like to thank Dr. Annamaria Basili, Chief, Department of Audiology and Speech Pathology, Fort Howard Veterans Administration Medical Center, for permission to test the patients. We are indebted to the entire staff of that department for their continued cooperation, and for their many useful comments on the research reported. We also thank Michael Giordano, Conrad Selnick, and Susan Baisley for their assistance in data analysis. A version of this paper was presented at the annual meeting of B.A.B.B.L.E., Niagara Falls, Canada, March, 1979     

Well-Being Indicators and Convergence Across Italian Regions

This article studies convergence across Italian regions by means of two composite indicators of socio-economic progress reflecting the multidimensional nature of human well-being. The first composite indicator includes, other than household disposable income in Italy, two sub-indicators regarding health and education; the second composite indicator considers, in addition to those considered by the former, three further sub-indicators relating to the quality of the socio-institutional context, age and gender disparities in the labor market and regional competitiveness. The data base of the 17 variables or indexes used to construct the six abovementioned sub-indicators cover the period from 1998 to 2008. We assess the existence of both σ and γ- convergence; the latter computed by means of Kendall′s index. Consistent with the findings in other European countries that also use composite economic and quality of life indicators we find evidence of regional σ-convergence in well-being, but do not observe significant processes of intra-distributional mobility. In other words, while dispersion across Italian regions in terms of well-being levels declined in the period, the regional ranking remained substantially unchanged.     

Time and rate measures in choice transitions

Three experiments with pigeons studied the relation between time and rate measures of behavior under conditions of changing preference. Experiment 1 studied a concurrent chain schedule with random-interval initial links and fixed-interval terminal links; Experiment 2 studied a multiple chained random-interval fixed-interval schedule; and Experiment 3 studied simple concurrent random-interval random-interval schedules. In Experiment 1, and to a lesser extent in the other two experiments, session-average initial-link wait-time differences were linearly related to session-average response-rate differences. In Experiment 1, and to a lesser extent in Experiment 3, ratios of session-average initial-link wait times and response rates were related by a power function. The weaker relations between wait and response measures in Experiment 2 appear to be due to the absence of competition between responses. In Experiments 1 and 2, initial-link changes lagged behind terminal-link changes. These findings may have implications for the relations between fixed- and variable-interval procedures and suggest that more attention should be paid to temporal measures in studies of free-operant choice.     

The Strategy and Attribution Questionnaire: Psychometric properties of a Lithuanian translation in an adolescent sample

The present study provides a preliminary validation of the Lithuanian version of the Strategy and Attribution Questionnaire (SAQ, Nurmi, et al., 1995), a self-reported measure of social and cognitive behavioral strategies. An attempt to validate SAQ subscales was made by correlating them with the Youth Self-Report (Achenbach, 1991) and school grades. This was done with a sample of 14- to 17-year-old adolescents (N= 734). The results showed that although internal consistency reliabilities were good, they were lower when compared with the original version of SAQ. The SAQ subscales were moderately associated with various validity criteria, such as anxiety/depression, withdrawal, social problems and somatic complaints and school grades. Results also showed moderate correlations between similar strategic components across achievement and affiliative situations. The results provide preliminary evidence for concurrent validity of the Lithuanian version of SAQ.     

Use of the ten-point clock test to compare executive functioning across 24 months in patients with subcortical vascular dementia

The Ten-point Clock Test can be used to identify early forms of Alzheimer's disease because it is reliable, well accepted, and easily administered at the bedside. Nevertheless, its clinical role in the detection of early dementia and its correlations with other cognitive processes is still under investigation. Vascular dementia is an uncertain nosological entity, in which unevenly distributed patterns of cognitive deficits comprising slowing of cognitive processing and impairment of executive function occur. The present study assessed how the Clock Test scores correlated with a number of other neuropsychological and functional tests in a sample of 144 patients with vascular dementia, who were followed for a period of 24 mo. At baseline, at 12 mo. and at 24 mo. subjects were administered a battery of tests, including the Mini-Mental State Examination, word fluency, visuospatial skills, an evaluation of hetero- and autotopognosia (knowledge of self), the Proverbs Test, and the Ten-point Clock Test. For these patients scores on the Clock Test correlated significantly with semantic abilities, with abstract reasoning capacities, visuospatial perception, and with right and left recognition.     

Timing in choice experiments

In Experiment 1, pigeons chose between variable- and fixed-interval schedules. The timer for 1 schedule was reset by a reinforcement on that schedule or on either schedule. In both cases, the pigeons timed reinforcement on each schedule from trial onset. The data further suggest that their behavior reflects 2 independent processes: 1 deciding when a response should be emitted and responsible for the timing of the overall activity, and the other determining what this response should be and responsible for the allocation of behavior between the 2 response keys. Results from Experiment 2, which studied choice between 2 fixed-interval schedules, support those 2 conclusions. These results have implications for the study of operant choice in general.