A disfluency descriptor digest for clinical use

A clinical form to be used in identifying which of a set of fluency eliciting techniques might be used most advantageously in therapy with individual stutterers is described.     

Constraints on Pavlovian conditioning of the pigeon: Relative conditioned reinforcing effects of red-light and tone CSs paired with food

Recent Pavlovian conditioning experiments presented all possible CS-US combinations of red-light and tone CSs and food and shock USs to separate groups of pigeons. Pigeons receiving shock USs demonstrated conditioned head raising followed by prancing to both CSs, but CRs were acquired more rapidly to tone than to red light. Although pigeons receiving food USs rapidly acquired a conditioned response of pecking to the red-light CS, there was no evidence of conditioned responding in groups receiving tone-food pairings. This outcome left open the possibility that Pavlovian pairings of tone and food may have resulted in association formation that was not revealed in performance. The present series of experiments attempted to reveal that association, using an indirect method of assessment, conditioned reinforcement. Experiment 1 demonstrated that both red light and tone paired with food became positive conditioned reinforcers, suggesting that an association between tone and food was formed in the same number of Pavlovian conditioning trials that previously failed to yield any direct evidence of conditioning. Experiment 2, which presented fewer conditioning trials, revealed that the tone-food association was formed less rapidly than the red light-food association. Experiment 3 demonstrated that the observed outcomes were not attributable to unconditioned, rather than conditioned, reinforcing effects of the Css.     

Extinction of the context and latent inhibition

The hypothesis that latent inhibition could be reduced by extinguishing the experimental context, that is, exposing the rats to the context between exposure to the conditional stimulus (CS) and conditioning, was tested. All experiments used the conditioned emotional response procedure. In Experiment 1, extinction was not effective when the animals were exposed to the clicker 40 times off the baseline of responding for food and when the clicker CS was partially reinforced with shocks during the test phase. In Experiments 2 and 3, latent inhibition could be reduced by extinction if the animals were exposed to the CS 24 or 16 times on-baseline, and if continuous reinforcement was used during the test. In Experiments 4, 5, and 6, we attempted to determine which variable was responsible for the discrepant results. In Experiment 4, extinction was effective with 20 or 40 on-baseline exposures to the CS, using continuous reinforcement during the test. In Experiment 5, extinction was not effective with exposure on- or off-baseline, using 24 exposures and partial reinforcement. Finally, in Experiment 6, extinction reduced latent inhibition using continuous, but not partial, reinforcement with 40 exposures off-baseline. From these results, we concluded that Wagner's model of habituation was not sufficient to account for latent inhibition and that a hybrid model, using both associative and cognitive representational processes, was necessary.     

On the study of statistical intuitions

The study of intuitions and errors in judgment under uncertainty is complicated by several factors: discrepancies between acceptance and application of normative rules; effects of content on the application of rules; Socratic hints that create intuitions while testing them; demand characteristics of within-subject experiments; subjects' interpretations of experimental messages according to standard conversational rules. The positive analysis of a judgmental error in terms of heuristics may be supplemented by a negative analysis, which seeks to explain why the correct rule is not intuitively compelling. A negative analysis of non-regressive prediction is outlined.     

Automatic access of the meanings of ambiguous words in context: Some limitations of knowledge-based processing

Five experiments are described on the processing of ambiguous words in sentences. Two classes of ambiguous words (noun-noun and noun-verb) and two types of context (priming and nonpriming) were investigated using a variable stimulus onset asynchrony (SOA) priming paradigm. Noun-noun ambiguities have two semantically unrelated readings that are nouns (e.g., PEN, ORGAN); noun-verb ambiguities have both noun and verb readings that are unrelated (e.g., TIRE, WATCH). Priming contexts contain a word highly semantically or associatively related to one meaning of the ambiguous word; nonpriming contexts favor one meaning of the word through other types of information (e.g., syntactic or pragmatic). In nonpriming contexts, subjects consistently access multiple meanings of words and select one reading within 200 msec. Lexical priming differentially affects the processing of subsequent noun-noun and noun-verb ambiguities, yielding selective access of meaning only in the former case. The results suggest that meaning access is an automatic process which is unaffected by knowledge-based (“top-down”) processing. Whether selective or multiple access of meaning is observed largely depends on the structure of the ambiguous word, not the nature of the context.     

The secretary problem as a model of choice

The finite “secretory problem” in dynamic programming generates a set of mathematically optimal criteria for search strategies in sequential decisions. One of the limitations on its applicability has been its failure to allow for the uncertainty of whether or not a choice alternative which has been inspected sometime previous to the present, will be “available.” In this paper, extensions of the model are presented which incorporate not only a parameter for the uncertain availability of previous alternatives, but for the uncertain availability of an alternative currently being observed. The paper emphasizes socalled heuristic strategies which may be used to approximate optimal solutions, and which entail very reasonable demands on the processing capacity of the decision-maker. Laboratory realizations and potential applications are discussed.     

Effects of altering outcome expectancies on pigeons' delayed conditional discrimination performance

An outcome-expectancy mediation theory of learning was tested in a series of transfer experiments with pigeons. The principal technique employed was a delayed two-choice conditional discrimination in which the subject's correct choice yielded a food reward on one kind of trial and a feedback tone on the other. According to the theory, this task engenders two-link mediational chains in that each conditional cue controls a particular outcome expectancy (S-E link) and the expectancy, in turn, cues a specific choice response (E-R link). Relative to the hypothetical mediators established by preceding training, transfer problems required either the same mediational chains, the alteration of one link in each chain, or the alteration of both links in both chains for optimal performance. The results of four separate transfer experiments confirmed detailed theoretical predictions, including that of an unusual nonmonotonic transfer effect. The relation of the present theory to earlier mediation theories is discussed.     

Semantic aphasia: A neglected entity

Three cases of semantic aphasia are reported. Computerized brain tomography showed bilateral temporo-parieto-occipital junction hemorrhages in one patient, and left parieto-occipital junction infarctions in the other two patients. The auditory comprehension defect of the three patients was characterized by preserved understanding of single words and impaired understanding of grammatically complex constructions. It is suggested that this comprehension defect reflects an inability to fully grasp the meaning of words and grammatical constructions imbued with spatial or quasi-spatial significance. Each of the three patients showed a complex spatial disorder that included constructional apraxia, spatial agnosia, and elements of Gerstmann's syndrome. The aphasic as well as the spatial disorder of semantic aphasics may be manifestations of a common defect in the perception of spatial relationships produced by left temporo-parieto-occipital region damage.     

An in depth, astute, comprehensive, and erudite attempt at categorization of stuttering theorists

The purpose of this paper is to make the reader aware of the various theoretical categories into which people who have been productive in the area of stuttering can be “slotted.” Readers are encouraged to read the characteristics, as I conceive of them, of each group of people and then see where their favorite “authorities” (which in many cases will undoubtedly include themselves) fit.