Systems approach to the concept of niche

Conclusion The systems approach to niche presented herein stands as an example of the unifying potential of mathematical system theory when applied to concepts and principles of ecology. Beginning with subjective concepts from the naturalistic tradition, the niche was framed in the formalism of general system theory. So modeled, it appeared as a restriction of a more general construct, the environ. Both niches and environs are implementable in the context of ecosystem models, and with the growing ability of ecologists to construct such models, system theoretic niches and environs both should serve in the future to clarify old problems of ecology, and make it possible to raise new classes of problems. The nature of niches, always difficult conceptually for the ecologist, may now give way to further development, both theoretical and empirical.     

A twin study of specific behavioral problems of socialization as viewed by parents

Our study focused on the etiology of specific behavioral problems rather than on a global syndrome such as hyperactivity. As a first step in studying specific behavioral problems, we revised the Conners (1970) Parent Symptom Rating questionnaire to improve its factor structure. Our revised instrument and the testretest reliabilities of its 12 scales are described. A classical twin analysis comparing intraclass correlations for 54 pairs of identical twins and 33 pairs of same-sex fraternal twins indicated substantial genetic influence on behavioral problems in schoolaged children. We wish to express our gratitude for the Spencer Foundation's support of this research.     

Focused memory search in fact retrieval

Several studies of fact retrieval have shown that the more facts a person learns about a concept, the longer it takes him or her to retrieve any of these facts. This result has been interpreted to mean that retrieval of a fact about a concept involves a search of all facts stored in memory with that concept. In the present study, it is suggested that retrieval involves not an unfocused search of all facts stored with a concept, but rather a focused memory search that examines relevant stored facts and ignores irrelevant information. This argument is supported by three experiments in which subjects first learned simple facts (e.g., “The banker likes horses”) and then made speeded true-false decisions for test probes le.g., “The banker likes elephants”). Specifically, results suggest that facts stored with a concept may be organized into subsets. For example, a person’s knowledge about Richard Nixon might be organized into subsets concerning Nixon’s resignation, his trips to China, his family, and so on. The data further suggest that a person attempting to retrieve a fact about a concept (e.g., the name of Nixon’s wife) may simply decide which subset is most likely to contain the desired fact (e.g., the subset concerning Nixon’s family) and search that subset. If the sought-for fact is found in this subset, the search process terminates. If, however, the desired information is not located, other subsets of facts may be searched before the retrieval attempt is given up. The notion that memory search focuses on relevant stored facts and ignores irrelevant information may help to explain why experts (i.e., people who know a large number of facts about a topic) do not experience great difficulty in retrieving facts in their areas of expertise.     

Interactive presentation in multitrial free recall

This paper explores whether free recall performance and organization can be facilitated using computer-controlled interactive presentation, where stimulus presentation on Trial N+1 depends on the individual subject’s prior recall history. A series of experiments investigated the effects of two types of response-contingent presentation order manipulations and of selective tagging manipulation designed to highlight the presentation of previously nonrecalled items. An initial experiment using 20-word lists showed no differences among groups, due to a ceiling effect. Two subsequent experiments, using longer lists (30 and 40 words), found that recall and subjective organization were increased by selective tagging and by presentation orders that preserved the subject’s prior order of recall. The results demonstrate that subjects’ previous recall histories contain information that can be used to facilitate recall. The potential of other interactive manipulations is discussed.     

Representation of inflected nouns in the internal lexicon

The lexical representation of Serbo-Croatian nouns was investigated in a lexical decision task. Because Serbo-Croatian nouns are declined, a noun may appear in one of several grammatical cases distinguished by the inflectional morpheme affixed to the base form. The grammatical cases occur with different frequencies, although some are visually and phonetically identical. When the frequencies of identical forms are compounded, the ordering of frequencies is not the same for masculine and feminine genders. These two genders are distinguished further by the fact that the base form for masculine nouns is an actual grammatical case, the nominative singular, whereas the base form for feminine nouns is an abstraction in that it cannot stand alone as an independent word. Exploiting these characteristics of the Serbo-Croatian language, we contrasted three views of how a noun is represented: (1) the independent-entries hypothesis, which assumes an independent representation for each grammatical case, reflecting its frequency of occurrence; (2) the derivational hypothesis, which assumes that only the base morpheme is stored, with the individual cases derived from separately stored inflectional morphemes and rules for combination; and (3) the satellite-entries hypothesis, which assumes that all cases are individually represented, with the nominative singular functioning as the nucleus and the embodiment of the noun’s frequency and around which the other cases cluster uniformly. The evidence strongly favors the satellite-entries hypothesis.     

Implications for phonetic symbolism: The relationship between pure tones and geometric figures

In studies of phonetic symbolism, the most commonly cited attribute of speech relevant to the phenomenon has been frequency. The present study was conducted in order to examine the relationship between pure tone frequencies and geometric figures. A pure tone oscillator was constructed which produced tones in a continuous sweep from 40–12,250 Hz. Six geometric shapes were employed and varied along three binary dimensions (size, complexity, and density) producing a total of 48 stimulus figures. Twelve male and twelve female subjects adjusted pure tone frequencies until they best fit the visually presented geometric figure in a complete within-subject, block-randomization design of 48 trials. There was consistency in the assignment of pure tone frequencies to the dimensions of the geometric figures. Round figures (circles and ellipses) generally received lower frequency assignments than other figures, and the shape by size interaction was also found to be statistically significant. The results are interpreted in light of recent research in psycholinguistics and in particular to the hypothesis of a universal phonetic symbolism.This research was a portion of a Master's thesis submitted to the University of Nevada, Las Vegas, by Michael W. O'Boyle, who is now at the University of Southern California.     

The use of averaged electroencephalic response techniques in the study of auditory processing related to speech and language

This paper reviews a number of studies done by the authors and others, who have utilized various averaged electroencephalic response (AER) techniques to study speech and language processing. Pertinent studies are described in detail. A relatively new AER technique, auditory brainstem responses (ABR), is described and its usefulness in studying auditory processing activity related to speech and language is outlined. In addition, a series of ABR studies, that have demonstrated significant male—female differences in ABR auditory processing abilities, is presented and the relevance of these data to already established differences in male—female language, hearing, and cognitive abilities is discussed.