The effects of a variety of instructions on human fixed-interval performance

College students were instructed to press a button for points under a single reinforcement schedule or under a variety of reinforcement schedules. Instructions for a single schedule were either specific or minimal. Instructions on a variety of schedules involved specific instructions on eight different schedules of reinforcement. Subsequent to the varied training, responding under a fixed-interval schedule occurred at a low rate. Both the minimal and specific instruction training led to fixed-interval responding that was similar to the responding exhibited during training. These findings suggest that under certain conditions instructed behavior is sensitive to changes in contingencies.     

Preference for simple interval schedules of reinforcement in concurrent chains: Effects of segmentation ratio

A concurrent-chains procedure was used to examine pigeons' preferences between segmented and unsegmented terminal-link schedules of reinforcement. During the initial link, a pair of independent, concurrent variable-interval 60-s schedules was in effect. In the terminal link, reinforcement was provided by a chain fixed-interval fixed-interval schedule on one key and by a simple fixed-interval schedule with an equal interreinforcement interval in the other. The relative duration between the first and second components (segmentation ratio) in the terminal-link chained schedule was systematically varied while the terminal-link duration was kept constant at either 15 s or 30 s in two sets of conditions. With few exceptions, the simple schedule was preferred to the chained schedule. Furthermore, this preference was inversely related to the size of the segmentation ratio in the segmented schedule. When the segmentation ratio was smaller than 1:1, preference was more extreme for a 30-s condition than for a 15-s condition. However, preference decreased more rapidly in conditions with the longer terminal-link duration when the ratio increased. Taken together, these results were consistent with previous findings concerning the effect of the terminal-link duration on choice between segmented and unsegmented schedules. In addition, the data suggested that segmentation ratio in a segmented schedule constitutes another potent factor influencing preference for the unsegmented schedule.     

Items bundles

An item bundle is a small group of multiple choice items that share a common reading passage or graph, or a small group of matching items that share distractors. Item bundles are easily identified by paging through a copy of a test. Bundled items may violate the latent conditional independence assumption of unidimensional item response theory (IRT), but such a violation would not typically suggest the existence of a new fundamental human ability to read one specific reading passage or to interpret one specific graph. It is important, therefore, to have theoretical concepts and empirical checks that distinguish between, on the one hand, anticipated violations of latent conditional independence within item bundles, and, on the other hand, violations that cannot be attributed to idiosyncratic features of test format and instead suggest departures from unidimensionalty. To this end, two theorems on unidimensional IRT are extended to describe observable item response distributions when there is conditional independencebetween but not necessarilywithin item bundles.The author is grateful to Ivo Molenaar and the referees for many helpful suggestions, and to D. Thayer for assistance with computing.     

A model for repeat paired comparison preference tests

A model is proposed that describes subject behavior on repeat paired comparison preference tests. The model extends prior work in this area in that it explicitly allows for abstentions and permits the derivation of individual true scores for discrimination ability as well as conditional estimates of proportionate preference. With these results, the properties of a paired comparison test can be thoroughly explored. An empirical example is presented, and test design issues are considered. In particular, repeat paired comparison preference tests are shown to be inherently less efficient discrimination tests than are pick 1 of 2 tests.     

Correspondence between definitions and procedures: A reply to Stokes, Osnes, and Guevremont

Stokes, Osnes, and Guevremont's (1987) implicit definition of correspondence classes appears close to ours (Matthews, Shimoff, & Catania, 1987). Their definition, however, is fundamentally procedural and thus may have to be modified as experimental methodologies are refined. The advantage of our contingency-space analysis is that it is independent of specific procedures and focuses attention on problems inherent in some procedural definitions. Specifically, a contingency-space analysis addresses the issue of distinguishing specific instances from classes and reminds us that correspondence can be identified as a class only on the basis of observing a population of opportunities for say/do sequences in which the subject sometimes does not say.     

The effect of signaled reinforcement availability on concurrent performances in humans

During Phase I, three female human subjects pressed a button for monetary reinforcement in two-component concurrent variable-interval schedules. Five different reinforcement frequencies were used in component A, whereas the reinforcement frequency in component B was held constant. Absolute rates of responding conformed to equations proposed by Herrnstein to describe concurent performances, and the ratios of the response rates and the times spent in the two components conformed to the matching law. During Phase II, the availability of reinforcement in component A was signaled by the illumination of a lamp. This resulted in suppression of response rates in component A and elevation of response rates in component B, these changes being reflected in a distortion of the matching relationship which took the form of a bias in favor of component B.     

Matching models in the analysis of cross-classifications

Inference models motivated by the combinatorial chance literature and the concept of object matching may be used in the analysis of a contingency table if the conditional assumption of fixed row and column totals is imposed. More specifically, by developing a matching reinterpretation for several problems of interest in the prediction analysis of cross-classifications—as defined by Hildebrand, Laing and Rosenthal, appropriate significance tests can be given that may differ from those justified by the more common multinomial models. In the course of the paper the distinction between a degree-1 statistic (based on the relationship between single objects) and a degree-2 statistic (based on the relationship between object pairs) is reviewed in some detail. Also, several specializations are presented to topics of current methodological importance in psychology; for instance, a number of references are made to the measurement of nominal scale response agreement between two raters.Partial support for this research was provided by the National Science Foundation through GSOC-77-28227.     

FINDERS,KEEPERS?: AN ANALYSIS AND VALIDATION OF A FREE-FOUND-AD POLICY

A SURVEY OF LOST AND FOUND CLASSIFIED SECTIONS IN METROPOLITAN AND SMALLER NEWSPAPERS REVEALED DISPARATE RATES BETWEEN LOST ADS AND FOUND ADS: Lost ads greatly outnumbered Found ads, probably because newspapers usually require the finders of lost personal property to pay for Found advertisements. The effect of a Free-Found-Ad policy on the rate of Found advertisements placed in the Lost and Found sections of three community newspapers was investigated using a multiple-baseline design. The results suggested that the Free-Found-Ad policy was effective in increasing the rates of Found ads in all three newspapers. To determine whether increases in Found ads resulted in increases in recovered property, a sample of individuals who placed Found ads were surveyed in both baseline and treatment conditions and asked if the found items had been claimed by their owners. The Free-Found-Ad policy appeared to be effective in increasing the amount of personal property returned. The study concluded that community newspapers can provide incentives to increase such help-giving or altruistic behaviors. The implications of this study for a general policy-research strategy are discussed.