Assessment of the relative importance of S+ and S− in rats using differential training on intercurrent discriminations

The present studies assessed the degree of stimulus control exerted by S+ and S? without confoundings of stimulus novelty and stimulus ambiguity. In Experiment 1, rats were trained on two intercurrent simultaneous discrimination problems with nine times more training given on one than the other. Then the animals were given transfer tests with re-paired stimuli. The results showed that S? exerts greater stimulus control than S+ in a two-choice simultaneous discrimination. Experiment 2 provided a test of the possibility that the relative degree of control by S? varies with different amounts of training. Three groups were trained on two intercurrent simultaneous discrimination problems; each group was given 7, 11, or 15 times more training on one problem than the other. Then transfer tests were given with re-paired stimuli. Again the results showed that S? exerts greater stimulus control than S+ in a two-choice simultaneous discrimination.     

Asymmetries in the perceptual span for Israeli readers

Native Israeli readers read Hebrew and English text as their eye movements were monitored. A window of text moved in synchrony with their eye movements and the window was either symmetrical about the fixation point or offset to the left or right. When subjects were reading Hebrew, the perceptual span was asymmetric to the left and when they were reading English it was asymmetric to the right. The results point out the importance of attentional factors in reading.     

Aphasics' selective deficits in appreciating grammatical agreements

This study attempted to dissociate in aphasic patients different aspects of grammatical capacity. Subjects were asked to evaluate sentences containing violations of agreements between pronouns and verbs. Agreements which are considered primarily structural in nature were violated (e.g., a surface object case like “them” placed in a surface subject sentential slot) while other violated agreements seemed to involve both structural and semantic information (e.g., lack of agreement between a pronoun and a verb in terms of the number of people performing the act). These violations were couched in one of three types of sentential frames which varied in terms of syntactic complexity (e.g., active declarative vs. passive syntactic voices). The results revealed that Broca's aphasics found agreement violations difficult to detect in complex syntactic frames. They were quite successful at detecting even violations of the largely structural “case” type of agreement, however, when couched in simpler syntactic frames. Fluent aphasics encountered more difficulty detecting violations of agreements involving both semantic and structural information than agreements which were primarily structural in nature, that is, regardless of the syntactic frame. These unique performance profiles suggest that Broca's aphasics may be agrammatic only with respect to certain aspects of a sentence's structure, and that fluent aphasics may also experience some selective—but different—grammatical deficits.     

Making and correcting errors during sentence comprehension: Eye movements in the analysis of structurally ambiguous sentences

Eye movements were recorded as subjects read sentences containing temporary structural ambiguities. In accord with the garden-path theory of sentence comprehension, shorter reading times were found for sentences conforming to certain independently motivated parsing strategies (late closure and minimal attachment) than for comparable sentences which violate these strategies. Further, longer fixation durations were associated with the very first fixation in the region of the sentence which disambiguated the sentence, suggesting that the human sentence-parsing mechanism operates in a rather systematic fashion, immediately computing the structural consequences of fixated material for the analysis of preceding material. The pattern of regressive eye movements did not conform to the view that the parsing mechanism automatically returns to the beginning of the sentence to revise an incorrect analysis of linguistic material nor did it support the view that the parsing mechanism systematically backtracks through the sentence until the source of the erroneous analysis is located. Rather, the pattern of regressions indicated that the parsing mechanism typically engages in selective reanalysis, exploiting whatever information it has available about the type of error it has committed to guide its reanalysis attempts. Finally, it is emphasized that an understanding of the parser's revision procedures is essential to an explanation of why certain linguistic structures cannot be successfully parsed by humans.     

Metalinguistic awareness and language development

Thirty-six 3- and 4-year-old children were given a battery of six metalinguistic tasks and two measures of language development: the Peabody Picture Vocabulary Test and a sentence comprehension test. The results clearly showed that the majority of preschoolers were able to make at least some metalinguistic judgments, and that metalinguistic performance improved with age. Furthermore, overall performance on the metalinguistic tasks was significantly correlated with each language measure when the effects of age were partialed out. In contrast, the correlation between age and metalinguistic performance was not significant once the effects of both language measures were partialed out. These data demonstrate that preschoolers' metalinguistic abilities are more extensive than has been previously acknowledged, and that they are closely tied to other aspects of language development at this time.     

The psychological representation of musical pitch in a tonal context

In this series of experiments, evidence was found for a complex psychological representation of musical pitch. The results of a scaling study, in which subjects judged the similarities between pairs of tones presented in an explicitly tonal context, suggest that musical listeners extract a pattern of relationships among tones that is determined not only by pitch height and chroma, but also by membership in the major triad chord and the diatonic scale associated with the tonal system of the context. Multidimensional scaling of the similarity ratings gave a three-dimensional conical structure around which the tones were ordered according to pitch height. The major triad components formed a closely related cluster near the vertex of the cone; the remaining diatonic scale tones formed a less closely related subset farther from the vertex; and, the nondiatonic tones, still farther from the vertex, were widely dispersed. The results also suggest that, in the psychological representation, tones less closely related to the tonality are less stable than tones closely related to the tonality, and that the representation incorporates the tendency for unstable tones to move toward the more stable tones in time, reflecting the dynamic character of musical tones. In the similarity ratings of the scaling study, tones less related to the tonality were judged more similar to tones more related to the tonality than the reverse temporal order. Furthermore, in a delayed recognition task memory performance for nondiatonic tones was less accurate than for diatonic tones, and nondiatonic tones were more often confused with diatonic tones than diatonic tones were confused with nondiatonic tones. These results indicate the tonality-specific nature of the psychological representation and argue that the perception of music depends not only on psychoacoustic properties of the tones, but also on processes that relate the tones to one another through contact with a well-defined and complex psychological representation of musical pitch.     

The effect of syntactic encoding on sentence comprehension in aphasia.

This study compared two levels of syntactic encoding with respect to their effect on aphasics' auditory comprehension. The same informational content was presented either as an embedded sentence or as two contiguous simplé propositions. A similar contrast was utilized to compare sentences containing relational terms of time, comparison, instrumentality, as well as sentences involving conjunction reduction, with parallel messages expressed in expanded, simplified form. A picture-verification paradigm was used. Comprehension was significantly enhanced only in the case of embedded sentences, with a tendency for Broca's aphasics to show the maximum effects.