Transfer of training of a new linguistic contrast in voicing

The present study examined the plasticity of the human perceptual system by means of laboratory training procedures designed to modify the perception of the voicing dimension in synthetic speech stimuli. Although the results of earlier laboratory training studies have been ambiguous, recently Pisoni, Aslin, Perey, and Hennessy (1982) have succeeded in altering the perception of labial stop consonants from a two-way contrast in voicing to a three-way contrast. The present study extended these initial results by demonstrating that experience gained from discrimination training on one place of articulation (e.g., labial) can be transferred to another place of articulation (e.g., alveolar) without any additional training on the specific test stimuli. Quantitative analyses of the identification functions showed that the new perceptual categories were stable and displayed well-defined labeling boundaries between categories. Taken together with the earlier findings, these results imply a greater degree of plasticity in the adult speech processing system than has generally been acknowledged in past studies.     

Organizational equity perceptions, employee job satisfaction, and departmental absence and turnover rates

Employee job satisfaction and perceptions of equitable treatment have been the topics of a great amount of behavioral research. Several theorists have suggested that one or the other may be related to organizational behaviors of employees such as absence and/or turnover. This longitudinal study examines the association of the two constructs, and, in a field setting, compares them as separate variables relating to absence and turnover. Employee perceptions of equitable treatment were found to be stronger predictors of absence and turnover than were job satisfaction variables.     

The effect of amplitude comodulation on auditory object formation in sentence perception.

To comprehend speech in most environments, listeners must combine some but not all sounds from across a wide range of frequencies. Three experiments were conducted to examine the role of amplitude comodulation in performing an essential part of this function: the grouping together of the simultaneous components of a speech signal. Each of the experiments used time-varying sinusoidal (TVS) sentences (Remez, Rubin, Pisoni, & Carrell, 1981) as base stimuli because their component tones are acoustically unrelated. The independence of the three tones reduced the number of confounding grouping cues available compared with those found in natural or computer-synthesized speech (e.g., fundamental frequency and simultaneity of harmonic onset). In each of the experiments, the TVS base stimuli were amplitude modulated to determine whether this modulation would lead to appropriate grouping of the three tones as reflected by sentence intelligibility. Experiment 1 demonstrated that amplitude comodulation at 100 Hz did improve the intelligibility of TVS sentences. Experiment 2 showed that the component tones of a TVS sentence must be comodulated (as opposed to independently modulated) for improvements in intelligibility to be found. Experiment 3 showed that the comodulation rates that led to intelligibility improvements were consistent with the effective rates found in experiments that examined the grouping of complex nonspeech sounds by common temporal envelopes (e.g., comodulation masking release; Hall, Haggard, & Fernandes, 1984). The results of these experiments support the claim that certain basic temporal-envelope processing capabilities of the human auditory system contribute to the perception of fluent speech.     

Discrimination of second-formant-like frequency transitions

Discrimination of two types of simulated single-second-formant: frequency transitions was studied, transitions where members of a stimulus set shared the same onset frequency and transitions where stimuli of a set shared the same offset frequency. Experiment 1 employed an adaptive procedure to measure just-noticeable differences for transitions that increased in frequency. Experiment 2 obtained complete psychometric functions, based on a three-interval,forced choice procedure,for transitions that either increased or decreased in frequency. In both experiments, better discrimination occurred for longer stimuli, measured in hertz/millisecond, and for transitions that shared the same onset frequency. There were no differences, in Experiment 2, between discrimination of rising and falling transitions. Results are considered from several theoretical perspectives.     

Discrimination of second-format-like frequency transitions

Discrimination of two types of simulated single-second-format frequency transitions was studied, transitions where members of a stimulus set shared the same onset frequency and transitions where stimuli of a set shared the same offset frequency. Experiment 1 employed an adaptive procedure to measure just-noticeable differences for transitions that increased in frequency. Experiment 2 obtained complete psychometric functions, based on a three-interval, forced-choice procedure, for transitions that either increased or decreased in frequency. In both experiments, better discrimination occurred for longer stimuli, measured in hertz/millisecond, and for transitions that shared the same onset frequency. There were no differences, in Experiment 2, between discrimination of rising and falling transitions. Results are considered from several theoretical perspectives.     

Enhancing Students' Engagement by Increasing Teachers' Autonomy Support

Engagement refers to the behavioral intensity and emotional quality of a person's active involvement during a task. Recognizing the benefits highly engaged people experience, we tested whether classroom teachers could incorporate the relatively foreign concept of autonomy support into their motivating styles as a way to promote their students' engagement during instruction. Teachers in an experimental group and teachers in a delayed-treatment control group received information and guidance consistent with self-determination theory on how to support students' autonomy. Over a series of 3 classroom observations, trained raters scored each teacher's autonomy support and 2 measures of their students' engagement–task involvement and influence attempts. Trained teachers displayed significantly more autonomy-supportive behaviors than did nontrained teachers. Further, the more teachers used autonomy support during instruction, the more engaged were their students. This was true on both measures of engagement.     

Some perceptual dependencies in speeded classification of vowel color and pitch

Wood (1975) suggested that information specifying consonant identity is dependent on the earlier processing of pitch. Is vowel identification also dependent on the prior processing of pitch? In contrast with the results obtained with consonants, Kuhl (1975, 1976) reported that infants responded selectively to differences in vowel color when pitch varied but not to differences in pitch when vowel color varied. Miller (1978) has also reported that adults show mutual, symmetric interference effects in speeded classification of vowel color and pitch, In the present study, judgments of vowel color and pitch were examined in a reaction time task in order to assess the effects of the relative discriminability of vowel and pitch quality on speeded classification. In addition, we also compared the classification of isolated vowels to vowels in consonantal context. The overall results were consistent with both Kuhl’s and Miller’s earlier findings but refine our understanding of the interaction between various dimensions by showing that vowel identification is also dependent on the processing of pitch information. Such an interaction, however, becomes evident only when the processing dependencies are examined across a wide range of stimulus values for each dimension. The present findings provide additional information about the nature of processing dependencies among dimensions in speech and the methods by which such dependencies may be studied.     

The effect of amplitude modulation on intelligibility of time-varying sinusoidal speech in children and adults

Although researchers are currently studying auditory object formation in adults, little is known about the development of this phenomenon in children. Amplitude modulation has been suggested as one of the characteristics of the speech signal that allows auditory grouping. In this experiment, we evaluated children (4 to 13 years of age) and adults to examine whether children's ability to use amplitude modulation (AM) in perception of time-varying sinusoidal (TVS) sentences is different from that of adults, and whether there are developmental changes. We evaluated performance on recognition of TVS sentences (unmodulated, amplitude-comodulated at 25, 50, 100, and 200 Hz, and amplitude-modulated using conflicting frequencies). Overall, the youngest children performed more poorly than did older children and adults. However, difference scores, defined as the percentage of phonemes correct in a given modulation condition minus the percentage correct for the unmodulated condition, showed no significant effects of age. Unlike the findings of previous studies (Carrell & Opie, 1992), these results support the ability of modulation with conflicting frequencies to improve intelligibility. The present study provides evidence that children and adults receive the same benefits (or decrements) from amplitude modulation.     

The effect of amplitude comodulation on auditory object formation in sentence perception

To comprehend speech in most environments, listeners must combine some but not all sounds from across a wide range of frequencies. Three experiments were conducted to examine the role of amplitude comodulation in performing an essential part of this function: the grouping together of the simultaneous components of a speech signal. Each of the experiments used time-varying sinusoidal (TVS) sentences (Remez, Rubin, Pisoni, & Carrell, 1981) as base stimuli because their component tones are acoustically unrelated. The independence of the three tones reduced the number of confounding grouping cues available compared with those found in natural or computersynthesized speech (e.g., fundamental frequency and simultaneity of harmonic onset). In each of the experiments, the TVS base stimuli were amplitude modulated to determine whether this modulation would lead to appropriate grouping of the three tones as reflected by sentence intelligibility. Experiment 1 demonstrated that amplitude comodulation at 100 Hz did improve the intelligibility of TVS sentences. Experiment 2 showed that the component tones of a TVS sentence must be comodulated (as opposed to independently modulated) for improvements in intelligibility to be found. Experiment 3 showed that the comodulation rates that led to intelligibility improvements were consistent with the effective rates found in experiments that examined the grouping of complex nonspeech sounds by common temporal envelopes(e.g., comodulation masking release; Hall, Haggard, & Fernandes, 1984). The results of these experiments support the claim that certain basic temporal-envelope processing capabilities of the liunian auditory system contribute to the perception of fluent speech.     

Discrimination of differences in digitally manipulated phoneme length during speech

The present study investigated differences in the thresholds of phoneme duration in word and sentence contexts by participants' sex. In the word condition, 27 participants listened to two pairs of words in a dual pair discrimination task. One pair contained the same durations of /s/, and the other pair contained different durations of /s/. Participants were to select the pair which contained different durations of /s/ in the words. In the sentence condition, the other set of 27 participants listened to two pairs of sentences and selected the pair containing different durations of /s/ in the sentences. Throughout these tasks, the participants' just-noticeable-difference and trials-to-completion were analyzed. The results showed that the participants demonstrated better performance in detecting just-noticeable-difference in the sentence condition than in the word condition. In addition, a sex difference was found in just-noticeable-difference in both conditions with better performance in men than women. No significant differences in trials-to-completion were found in either condition.