Search PubMed⌕ Search

Biomedical subjects

N Cowan

Publications and source records attributed to N Cowan.

At least 73 records · Page 4Linked to original sources
PubMed1987

Auditory sensory storage in relation to the growth of sensation and acoustic information extraction.

A brief, vivid phase of auditory sensory storage that outlasts the stimulus could be used in perception in two ways: First, all of the neural activity resulting from the stimulus, including that of the sensory store, could contribute to a sensation of growing loudness; second, the sensory store could permit the continued extraction of information about the sound's acoustic properties. This study includes a task for which these two processes lead to different predictions; a third prediction is based on the two processes combined. The task required loudness judgments for two brief tones presented with a variable intertone interval. The results of Experiments 1-3 were as one would expect if both the growth of sensation and information extraction contributed to the pattern of loudness judgments. Experiment 4 strengthened the two-process account by demonstrating the separability of the two processes. Approaches to mathematical modeling of these results are discussed.

Adult↗
PubMed1986

The use of auditory and phonetic memory in vowel discrimination.

A commonly held assumption about memory for speech is that auditory memory is referred to only if phonetic memory does not contain the information needed for a particular trial. However, this assumption is in conflict with recent evidence [Crowder, J. Exp. Psychol.: Learning, Memory, Cognition 8, 153-162 (1982); Repp et al., J. Exp. Psychol.: Human Perception Performance 5, 129-145 (1979)]. The present study provides additional data to help determine how auditory and phonetic memory are used in a vowel discrimination task, and what happens during memory decay. Experiment 1 was conducted to determine whether performance levels decline at similar rates on between- and within-category AX vowel comparison trials when certain methodological problems are removed. This was confirmed. Experiment 2 demonstrated that in the AX task there is a vowel order effect, as Repp et al. found, but that this effect increased across interstimulus delay intervals, in contrast to their findings. The results can be accommodated with a model in which the memory for a vowel is represented as a small, bounded area within the vowel space, and in which memory decay is represented by the expansion of that bounded area over time.

Adolescent↗
PubMed1984

Infant speech recognition in multisyllabic contexts.

In 2 infant speech recognition experiments using trisyllabic sequences, the amount of redundancy within nontarget, context syllables was manipulated. Infants 6 1/2 months old were trained to discriminate the syllables [ba] versus [du] in contexts that were either redundant (e.g., [ko ba ko] or [ti ba ti]) or mixed (e.g., [ko ba ti] or [ti ba ko]) A visually reinforced head-turning procedure was employed. In Experiment 1, context was manipulated between subjects, but in Experiment 2 each subject received all 4 contexts (2 redundant, 2 mixed). Infants consistently recognized the familiar target in all contexts, but did so more successfully in redundant than in mixed trisyllablic contexts. These results suggest that amount of speech redundancy may be an important factor in infants' perceptual capabilities.

Attention↗
PubMed1982

A fluent backward talker.

This report documents the ability of a man to reverse the order of segments within words, so quickly that the simultaneous translation of forward speech into reversed speech was possible. Transcriptions of recorded backward speech and several processing tasks were used to clarify this man's profile of unusual linguistic skills. Analyses of the background speech showed evidence of sensitivity to both phonemic and orthographic representations of the utterances.

Adult↗
PubMed1982

Mothers' perceptions of infant distress vocalizations.

In the present study the psychological and acoustic properties of the distress vocalizations of five 3-4-month-old infants were examined. Each vocalization was rated on a 5-point scale from "definitely fuss" to "definitely cry" by mothers on two home visits. On the first home visit, each mother rated a set of her own infant's vocalizations recorded 1/2 hour previously and presented in the order of occurrence. Three weeks later, on the second home visit, mothers were presented with the master tape that contained the vocalizations of all five infants in random order. Analyses of the judgment data and acoustic parameters of the vocalizations revealed that (a) mothers were able to rate infant vocalizations reliably along a fuss-cry continuum, both shortly after these vocalizations were produced and 3 weeks later with fewer available nonacoustic, contextual cues; (b) mothers relied upon mean and peak intensity, mean F2 frequency, the ratio of F1 to F2, and mean duration in their judgments of infant cries versus fusses; and (c) although there was a high level of rating consistency across mothers, there were some discrepancies between visit 1 and 2 ratings due to the contribution of context cues present on visit 1 only.

Acoustics↗
PubMed1982

Echoic storage in infant perception.

Preperceptual auditory of "echoic" storage was investigated in 8-9 week-old infants using a modification of an adult masking paradigm and a nonnutritive sucking discrimination procedure. Experiment 1 provided validation of a new version of the nonnutritive sucking procedure using the standard stimulus contrast [ba] versus [pa]. In experiment 2, infants were presented with repeating pairs of brief vowels with a stimulus onset asynchrony (SOA) of 50 msec for each pair. Within each series, the first vowel in a pair changed (backward masking), the second vowel changed (forward masking), or neither vowel changed (control). Discrimination of the changed occurred in the forward- but not in the backward-masking condition. In experiment 3, discrimination occurred in a backward-masking condition with an SOA of 400 msec, but not with an SOA of 250 msec or in a control condition. In conjunction with the adult literature, these results suggest that echoic storage contributes to auditory perception in infancy, as in adulthood, but that the useful lifetime of an echoic trace may be longer in infancy.

Auditory Perception↗
PubMedDate not supplied

Can we resolve contradictions between process dissociation models?

Wainwright and Reingold (1996) presented equations for various versions of the process dissociation procedure that has been used to separate conscious and unconscious memory process. In the present reply it is suggested that these equations, though helpful, may not capture some of the key theoretical possibilities that could help to resolve apparent contradictions and paradoxes in the empirical literature. Specifically, there could be an independence of processes that might be estimated to a sufficient degree of accuracy for some theoretical purposes despite a violation of the assumption of stochastic independence.

Humans↗
PubMedDate not supplied

Constraints on awareness, attention, processing, and memory: some recent investigations with ignored speech.

We discuss potential benefits of research in which attention is directed toward or away from a spoken channel and measures of the allocation of attention are used. This type of research is relevant to at least two basic, still-unresolved issues in cognitive psychology: (a) the extent to which unattended information is processed and (b) the extent to which unattended information that is processed can later be remembered. Four recent studies of this type that address these questions in various ways (Cowan, Lichty, & Grove, 1990; Wood & Cowan, 1995a,b; Wood, Stadler & Cowan, in press) are reviewed as illustrations. We conclude from these studies that (a) unattended information appears to be partially processed automatically, though attention enhances the processing considerably, and (b) the unattended information that is processed may not be retrievable in direct or many indirect memory tasks, though it remains possible that there is an automatically stored memory trace (e.g., one that could produce semantic priming).

Attention↗
PubMedDate not supplied

The role of attention in the development of short-term memory: age differences in the verbal span of apprehension.

In previous studies of memory span, participants have attended to the stimuli while they were presented, and therefore have had the opportunity to use a variety of mnemonic strategies. In the main portion of the present study, participants (first- and fourth-grade children, and adults; 24 per age group) carried out a visual task while hearing lists of spoken digits and received a post-list digit recall cue only occasionally, for some lists. Under these conditions, list information presumably must be extracted from a passively held store such as auditory sensory memory. The results suggest that each individual has a core memory capacity limit that can be observed clearly in circumstances in which it cannot be supplemented by mnemonic strategies, and that the capacity limit appears to increase with age during childhood. Other, attention-demanding processes also contribute to memory for attended lists.

Age Factors↗