Combined stimulus control over time allocation in response-independent schedules

Rats were exposed to concurrent schedules in which reinforcers occurred independently of behavior. In Experiment 1, rats could control time spent in the following conditions: (1) a light, (2) white noise, and (3) the absence of both light and noise. Response-independent reinforcers occurred at the same rate during the light and the noise and at either a higher rate or not at all in the absence of both stimuli. In subsequent tests, the rats spent more time in a light and noise compound than in either light or noise alone after the absence of both stimuli had signaled no reinforcers. When the absence of both stimuli had signaled a higher rate of reinforcement, however, the rats typically spent less time in the compound than in light or noise alone. In Experiment 2, rats could control time spent in the presence of a light and of a buzzer. The reinforcement rate in the light was twice that in the buzzer. In a later test, the rats spent more time in a light and buzzer compound than in the buzzer, but less time in the compound than in the light. The results show that additive summation, suppressive summation, and stimulus averaging of time allocation occur and that response rate differences between training stimuli are not necessary for these phenomena.     

Reading abilities of school-age stutterers

The reading abilities of 20 school-age stutterers and their matched normally fluent controls were assessed by means of the Woodcock Reading Mastery Tests. Results indicate that the reading abilities of school-age stutterers are not significantly different from those of school-age normals. Similarly, knowing whether a subject was classified as a stutterer or normally fluent speaker was of minimal assistance in predicting the subject's reading performance. These findings suggest that school-age stutterers' reading abilities are within normal limits. An individual stutterer, just like an individual normally fluent speaker, may exhibit “reading problems”; however, caution should be employed in extrapolating from one individual stutterer's reading performance to the reading abilities of all stutterers.     

The cognitive basis of the comprehension and production of relational terminology

The comprehension of big, little, and same number and the productio of relational terminology was assessed in 168 preschool children. Stimuli were used which varied the relationships of length, number, and density. Language comprehension and production were related to the complexity of cognitive operations required by the task. Specifically, comprehension was easier in the situations in which length and number were positively correlated than when length provided no cue to number. Comprehension was most difficult when length and number were negatively correlated. There was asymmetry in language comprehension such that the positive term big, was comprehended earlier than little in some tasks; there was also asymmetry in production in that the child was more likely to use language related to the positive pole than to the negative pole. These data were interpreted as providing support for theories of the cognitive basis of language acquisition.     

Origin of the speech apparatus and its reconstruction in fossils.

Renewed enthusiasm has produced provocative speculations in recent literature on the origin of speech. The purpose of the present investigation is to expose the adaptive renovations underlying the emergence of a “Vocal Tract” and from this to define its anatomical substrate which governs the biomechanics of speech production. The vocal tract is a double resonator tube coupled in series and composed of oral and pharyngeal cavities. Analysis is made of the crucial structural elements of this complex from detailed dissections in modern man and the study of modern and fossil hominid crania. The study focuses on relations of the skull base, jaw, hyoid bone and the contained tongue, pharynx and valvular devices, calling into question recent reconstructions built on classical Neanderthal skulls.     

The effect of Pavlovian stimuli on the acquisition of a new response

Three experiments explored the effects of response dependent stimuli which have had different types of contingent relationships with positive reinforcement. Results showed consistent differences in the effects of response dependent appetitive Pavlovian CS + s, CS ? s, and truly random control (TRC) stimuli on the acquisition of a new response. These differences were shown in both a free operant and a discrete-trial learning situation. Appetitive Pavlovian CS?s consistently produced lower levels of responding than did TRC stimuli, even in an experimental situation free of possible contrast effects. The results of these experiments extended a contingency analysis of acquired associations to appetitive conditioning and provided a clear demonstration of a conditioned reinforcement effect against a variety of control procedures.     

Problems with a false recognition paradigm for developmental memory research

Developmental changes in memory organization based on synonym and antonym relationships were examined in three experiments. Although Cramer (1973) claimed that second-grade children organized their memory for words based on synonym relationships while sixth-graders used antonyms, no support for this interaction was found. The present studies employed additional procedures in an attempt to replicate and extend Cramer's finding. Some inadequacies of a false recognition paradigm for developmental research are identified and some alternative analyses are proposed.     

Kindergarten children's use of category membership

Kindergarten children (N = 70) learned to order 12 photographically presented objects. The objects were well known and either unrelated or categorizable into two, three, four, or six well-known categories. Free recall was assessed. Results indicated that the children used category membership both to learn and to recall the items. However, they processed the list composed of six pairs of items at least as efficiently as lists composed of fewer but larger groups of items (including a list indexed as easiest through previous adult performance).     

Contingent reinforcement of lowered blood-alcohol levels in an outpatient chronic alcoholic

Recently. the proposition that alcohol abuse is an operant behavior and thus functionally related to its consequences has been investigated under experimental conditions. In controlled laboratory settings, in which inpatient chronic alcoholics are allowed access to alcoholic beverages, alcohol consumption has been markedly altered via operant strategies. Monetary rewards (Cohen et al., 1971), the opportunity to participate in an enriched environment (Cohen et al., 1971). and visits to a girlfriend (Bigelow et al., 1973) have been used as reinforcers for decreased drinking.Other investigators (Sulzer, 1965; Miller, 1972: Hunt and Azrin, 1973) have successfully applied similar contingency management techniques to alcoholics in the natural environment. However, failure to control for the influence of extraneous therapeutic variables (e.g., attention-placebo factors, job counseling) together with reliance on self-report measures of drinking behavior seriously limit the conclusiveness of these results. Objective assessment is particularly essential with operant techniques since consequent events must be systematically scheduled upon the occurrence or non-occurrence of drinking. Documentation of drinking in the natural environment is a difficult task since the alcoholic frequently consumes alcohol when he is alone. In lieu of direct observation, blood alcohol concentrations are an obvious means of objective assessment. Such data are most conveniently obtained via breath tests similar to the ones that law enforcement officers utilize to identify intoxicated motorists.The purpose of the present study was to investigate the influence of reinforcement contingencies on lowering blood alcohol concentrations obtained in an alcoholic's natural environment.     

The role of reference in children's acquisition of a miniature artificial language

Nursery school children were presented with a simple miniature artificial language in one of three conditions. In the first, the stimuli to which the words referred contained an inherent lawful relationship and the language syntax reflected this relationship. In the second, the stimuli contained an inherent lawful relationship but the language syntax did not reflect this relationship. In the third, no lawful relationship existed among the stimuli to which the words referred so the language syntax imposed an arbitrary relationship among stimuli. Subjects in the first group were able to produce more correct utterances than those in the other two groups when the stimuli to which the words referred were not present, suggesting that some form of semantic mediation mechanism was being used. Evidence from novel constructions indicates that for both groups using stimuli containing an inherent lawful relation there were interactions between semantic learning mechanisms and syntax learning mechanisms.     

Partial reinforcement effects and type of reward

In two experiments 68 rats were trained to bar press or run down a straight runway for food or for water under conditions of either continuous reinforcement or partial reinforcement. In both experiments, there was greater persistence of behavior which had been reinforced with food than with water. In Expt 2, the partial reinforcement extinction effect (PREE) was observed with food reward, but not with water.Within the context of the experimental procedures used, it can be concluded that the rat has mechanisms for developing persistence which are dependent on the specific motivational system involved. This conclusion is related to theories of partial reinforcement effects and to possible biological origins of the mechanisms.