Familial handedness and access to words, meaning, and syntax during sentence comprehension.

We compared right-handed familial dextral (FS-) and familial sinistral (FS+) participants who were aged either 10-13 years (children) or 18-23 years (adults). In word probe and associative probe tasks, FS+ adults responded faster than all other groups and FS+ children responded more slowly than all other groups. In the word probe task, only the FS- adults showed a significant effect of the serial position of the target word. We interpret these differences to support an analysis-by-synthesis model of comprehension in which individuals who differ in familial handedness and age emphasize different linguistic representations during comprehension. In general, FS+ individuals focus on words and meaning, while FS- individuals focus on syntactic representations. In FS+ individuals, age-related experiences with language produce a shift in responding from compositional meaning to words and their associations. In FS- individuals, age-related experiences with language produce a shift toward responding based more on detailed syntactic representations, including the serial order of words and possibly the structural roles of clauses.

Word-monitoring tasks interact with levels of representation during speech comprehension.

Researchers frequently use data from monitoring tasks to argue that constraints on meaning facilitate lower-level processes. An alternate hypothesis is that the processing level that a monitoring task requires interacts with discourse-level processing. Subjects monitored spoken sentences for a synonym (semantic match), a nonsense word (phonological match), or a rhyme (phonologically and semantically constrained matching). The critical targets appeared at the beginning of the final clause in two-clause sentences that began with if, which signals a semantic analysis at the discourse level, or with though, which maintains a surface representation. Synonym-monitoring times were faster for if than for though, nonsense word-monitoring times were faster for though than for if, and rhyme-monitoring times did not differ for if and though. The results show that conjunctions influence how listeners allocate attention to semantic versus phonological information, implying that listeners form these kinds of information independently.

Peripheral and cerebral asymmetries in the rat.

Rats learn a novel foraging pattern better with their right-side whiskers than with their left-side whiskers. They also learn better with the left cerebral hemisphere than with the right hemisphere. Rotating an already learned maze relative to the external environment most strongly reduces right-whisker performance; starting an already learned maze at a different location most strongly reduces left-whisker performance. These results suggest that the right-periphery-left-hemisphere system accesses a map-like representation of the foraging problem, whereas the left-periphery-right-hemisphere system accesses a rote path. Thus, as in humans, functional asymmetries in rats can be elicited by both peripheral and cortical manipulation, and each hemisphere makes qualitatively distinct contributions to a complex natural behavior.

Canonical and non-canonical syllable discrimination by two-day-old infants.

Canonical syllables may be important units in early speech perception as well as production. Twenty infants (mean age 51 hours) (and twenty controls) were tested for their ability to discriminate between members of syllable pairs which were either canonical (paet and taep) or non-canonical (pst and tsp). A discrimination learning method was used in which syllables signalled the availability of either a recording of the mother's voice or silence--one of which was presented if the infant began a sucking burst. Infants in the canonical condition changed sucking patterns during signals over an 18-minute experimental session and activated their mother's voice more than silence, consistent with previous experiments using mother's voice as a reinforcer. In the non-canonical condition, infants also changed sucking patterns but sucked more during the signal for quiet than mother's voice, contrary to previous findings. Differential sucking during the syllables indicated discrimination in both conditions, but infants responded differently depending upon whether the syllables were canonical or non-canonical. The activation of silence in the non-canonical condition may be the result of a preference for quiet, but it is better explained as a failure to progress to a level of differential responding that was reached by the canonical group.

On-line choice and the representation of serially structured stimuli.

Three groups of pigeons were trained to discriminate between a target temporal sequence, consisting of red, green, and blue, and distractor sequences consisting of all other combinations of these three colors presented on a pecking key. Response alternatives were provided during the course of the trial (on-line decisions) as well as the end of the trial (postsequence decisions). Different temporal phrasing patterns emphasized the first stimulus in the sequence, the final stimulus, or all stimuli equally. The phrasing pattern did not affect the speed of acquisition, but groups receiving emphasized stimuli relied more heavily on those stimuli than on the other stimuli for their discriminations. The patterns of both on-line choices during the sequence and terminal choices following the sequence were consistent with the use of hierarchical representations and inconsistent with a simple item-by-item prospective discrimination scheme.

Can an ape create a sentence?

More than 19,000 multisign utterances of an infant chimpanzee (Nim) were analyzed for syntactic and semantic regularities. Lexical regularities were observed in the case of two-sign combinations: particular signs (for example, more) tended to occur in a particular position. These regularities could not be attributed to memorization or to position habits, suggesting that they were structurally constrained. That conclusion, however, was invalidated by videotape analyses, which showed that most of Nim's utterances were prompted by his teacher's prior utterance, and that Nim interrupted his teachers to a much larger extent than a child interrupts an adult's speech. Signed utterances of other apes (as shown on films) revealed similar non-human patterns of discourse.

Serial learning in the pigeon.

Three pigeons learned to peck four colors in a particular sequence, regardless of how these colors were positioned on four response keys and without feedback following each response. This demonstrates that serial learning is possible in subprimate animals.

Segmentation in cinema perception.

Viewers perceptually segment moving picture sequences into their cinematically defined units: excerpts that follow short film sequences are recognized faster when the excerpt originally came after a structural cinematic break (a cut or change in the action) than when it originally came before the break.

Detection of a nonlinguistic stimulus is poorest at the end of a clause.

Subjects detected a brief near-threshold tone while encoding two-clause sentences for later report. The objective tone locations were at the end of the first clause, at the beginning of the second clause, or in the clause boundary. The effects of intensity variations of the speech signal were assessed by having subjects detect the tones in the same speech stimuli played backward. Tones at the end of a clause are relatively harder to detect than in other positions, comparing forward and backward speech. This supports the view that listeners are preoccupied with internal processes at the end of a clause.

Cerebral dominance in musicians and nonmusicians.

Musically experienced listeners recognize simple melodies better in the right ear than the left, while the reverse is true for naive listeners. Hence, contrary to previous reports, music perception supports the hypothesis that the left hemisphere is dominant for analytic processing and the right hemisphere for holistic processing.

The interaction of perceptual processes and ambiguous sentences.

General principles of speech perception resolve several experimental conflicts about whether listeners interpret one or all meanings of an ambiguous sentence We argue that during all ambiguous clause, both meanings are processed, but immediately after the clause over, it recoded with only one meaning retained This model resolves the apparently conflicting results of previous experimental, it also predicts that underlying structure ambiguity m incomplete clauses increases Comprehension time In complete clauses, ambiguity does not increase relative comprehension time; it mayreduce comprehension time for ambiguities whose interpretations are perceptually distinct in those tasks where either meaning is appropriate Two new experiments offer preliminary confirmation of these predictions.

What children do in spite of what they know.

New studies support the hypothesis that young children have basic cognitive capacities but utilize them inefficiently; older children aid these capacities with generally valid cognitive heuristics which produce poor performance on critical problems.