Some differences between phonetic and auditory modes of perception

When third-formant transitions are appropriately incorporated into an acoustic syllable, they provide critical support for the phonetic percepts we call [d] and [g], but when presented in isolation they are perceived as time-varying ‘chirps’. In the present experiment, both modes of perception were made available simultaneously by presenting the third-format transitions to one ear and the remainder of the acoustic syllable to the other. On the speech side of this duplex percept, where the transitions supported the perception of stop-vowel syllables, perception was categorical and influenced by the presence of a preposed [al] or [ar]. On the nonspeech side, where the same transitions were heard as ‘chirps’, perception was continuous and free of influence from the preposed syllables. As both differences occurred under conditions in which the acoustic input was constant, we should suppose that they reflect the different properties of auditory and phonetic modes of perception.     

Memory for item order and phonetic recoding in the beginning reader

A defect in immediate memory for item order is often attributed to poor beginning readers. We have supposed that this problem may be a manifestation of an underlying deficiency in the use of phonetic codes. Accordingly, we expected good and poor readers to differ in their ability to order stimuli that can be easily recoded as words and stored in phonetic form, but not in their ability to order nonlinguistic stimuli that do not lend themselves to phonetic recoding in short-term memory. The purpose of the present study was to test this hypothesis by examining the ability of good and poor readers to reconstruct the order of sets of briefly presented stimuli that varied in the extent to which they could be distinctively recoded into phonetic form: pictures of common objects versus nonrepresentational, “doodle” drawings. As expected, an interaction between reading ability and type of stimulus item was found, demonstrating the material-specific nature of poor readers' ordering difficulties. These findings support the hypothesis that a function of the phonetic representation is to aid in retention of order information, and that poor readers' ordering difficulties are related to their deficient use of phonetic codes.     

Internal-External Control and beliefs about automobile travel

It was hypothesized that the Internal-External Locus of Control dimension (Rotter, 1966) would predict reported feelings about automobile travel and attribution of responsibility for automobile accidents. Relative to Externals, Internals were found (a) to attribute responsibility for automobile accidents more to internal, controllable causes; (b) to report less anxiety when travelling via automobile; (c) to report wearing seatbelts more often; and (d) to experience automobile travel as more interesting and involving.     

Toward a theory of apractic syndromes

Theoretical development on human motor behavior has occurred largely independently of data on pathological movement disorders. This paper represents an initial attempt to interface findings from studies of apraxia and those of normal motor behavior with a view to formulating a common theoretical framework. Such an integration may ultimately aid in understanding the nature of skill acquisition and provide insights into the organization of motor systems. Three putative theoretical models of movement control are discussed with reference to apractic syndromes. The most commonly accepted view—the hierarchy—possesses properties such as linear transitivity and unidirectionality of information flow that render it inadequate in explaining functional plasticity in the central nervous system. The heterarchy, which incorporates reciprocity of function and circular transitivity, is a more likely candidate but suffers from an inability to regulate the degrees of freedom of the system. Our favored candidate is the coalition model which embodies heterarchical principles, but in addition, offers a solution to the problems of degrees of freedom and context for motor systems. Evidence is reviewed from apraxia of speech and limbs in terms of a coalitional style of control and an experimental approach, consonant with coalitional organization, is developed. We promote the claim that an understanding of apractic behavior—and perhaps motor systems in general—will benefit when clinicians and experimenters embrace a theory of context and constraints rather than a theory of commands as is currently in vogue.     

Second-order conditioning of Pavlovian conditioned inhibition

Two experiments are reported which investigated the conditioning of inhibition to a neutral stimulus as a result of its repeated pairing with a previouslyconditioned inhibitor. Both experiments employed a conditioned suppression technique with rat subjects. Experiment 1 detected the second-order inhibition through the retarded acquisition of concurrently administered excitatory conditioning. Experiment 2 found similar retardation in the acquisition of excitatory fear conditioning following previous second-order conditioning of inhibition to the stimulus. Implications are discussed for theories of the nature of inhibition and for second-order conditioning as an assessment technique.     

Different speech-processing mechanisms can be reflected in the results of discrimination and dichotic listening tasks

The relative peakedness of diotic ABX discrimination functions for certain speech stimuli and the relative magnitude of the right ear advantage that they yield in dichotic listening tasks have been thought to be functionally parallel measures of speech processing. The results of the present study suggest that this is not always the case.     

Speech perception and memory coding in relation to reading ability

Previous work has demonstrated that children who are poor readers have short-term memory deficits in tasks in which the stimuli lend themselves to phonetic coding. The aim of the present study was to explore whether the poor readers' memory dificit may have its origin in perception with the encoding of the stimuli. Three experiments were conducted with third grade good and poor readers. As in earlier experiments, the poor readers were found to perform less well on recall of random word strings and to be less affected by the phonetic characteristics (rhyming or not rhyming) of the items (Experiment 1). In addition, the poor readers produced more errors of transposition (in the nonrhyming strings) than did the good readers, a further indication of the poor readers' problems with memory for order. The subjects were tested on two auditory perception tasks, one employing words (Experiment 2) and the other nonspeech environmental sounds (Experiment 3). Each was presented under two conditions: with a favorable signal-to-noise ratio and with masking. The poor readers made significantly more errors than the good readers when listening to speech in noise, but did not differ in perception of speech without noise or in perception of nonspeech environmental sounds, whether noise-masked or not. Together, the results of the perception studies suggest that poor readers have a perceptual difficulty that is specific to speech. It is suggested that the short-term memory deficits characteristic of poor readers may stem from material-specific problems of perceptual processing.