Function Of Stimulus Magnitude Research Articles

Online monitoring of auditory feedback is sensitive to language experience.

It has been demonstrated that vocal responses to pitch perturbations vary as a function of stimulus parameter and can be modulated according to the specific demands of vocal task. The purpose of this cross-language study was to examine whether the online monitoring of auditory feedback is sensitive to language experience during vowel phonation. Native speakers of Cantonese and Mandarin participated in the experiments. They were asked to vocalize a vowel sound /u/ at their conversational pitch, during which their voice pitch feedback was unexpectedly shifted (±50, ±100, ±200, or ±500 cents, 200 ms duration) and fed back to them over headphones. The results showed that, as compared to previous findings in English speakers [Chen et al. (2007)], both Mandarin and Cantonese speakers produced smaller but faster responses to pitch perturbations. In addition, Mandarin speakers produced larger response magnitudes than Cantonese speakers, and the modulation of response magnitudes as a function of stimulus magnitude was observed in Cantonese but not in Mandarin speakers. These findings demonstrate that voice F0 control is language dependent. Further, the different patterns of vocal responses between Mandarin and Cantonese speakers indicate that this highly automatic feedback mechanism works within the specific tonal system of each language.

Effects of vocal pitch level and perturbation magnitude on the pitch-shift reflex

The purpose of the present study was to investigate the responsiveness of the pitch-shift reflex to small magnitude stimuli, vocal level, and pitch-shift direction. English speakers received pitch-shifted voice feedback (10, 20, 30, 40, and 50 cents, 200 ms duration) during vowel phonation at a high pitch and a low pitch level. Mean response magnitude increased as a function of stimulus magnitude, but when expressed as a percent of stimulus magnitude, declined from 100% with 10 to 37% with 50 cent stimuli. Response magnitudes were larger and latencies were shorter with a high pitch level (15.8 cents; 130 ms) than a low pitch level (12.8 cents; 152 ms). Similar results were found with downward stimuli compared to upward stimuli (15.7 cents versus 13.1 cents; 126 ms versus 155 ms). Data from the present study demonstrate that vocal response magnitudes are equal to small perturbation magnitudes, and they are larger and faster with a high-pitched voice and downward directed pitch stimuli. These results suggest that the audio-vocal system is optimally suited for compensating for small pitch rather than larger perturbations. Data also suggest the sensitivity of the audio-vocal system to voice perturbation may vary with pitch level.

Voice F responses to pitch-shifted voice feedback during English speech

Previous studies have demonstrated that motor control of segmental features of speech rely to some extent on sensory feedback. Control of voice fundamental frequency (F0) has been shown to be modulated by perturbations in voice pitch feedback during various phonatory tasks and in Mandarin speech. The present study was designed to determine if voice Fo is modulated in a task-dependent manner during production of suprasegmental features of English speech. English speakers received pitch-modulated voice feedback (+/-50, 100, and 200 cents, 200 ms duration) during a sustained vowel task and a speech task. Response magnitudes during speech (mean 31.5 cents) were larger than during the vowels (mean 21.6 cents), response magnitudes increased as a function of stimulus magnitude during speech but not vowels, and responses to downward pitch-shift stimuli were larger than those to upward stimuli. Response latencies were shorter in speech (mean 122 ms) compared to vowels (mean 154 ms). These findings support previous research suggesting the audio vocal system is involved in the control of suprasegmental features of English speech by correcting for errors between voice pitch feedback and the desired F0.

Event-related potentials to inspiratory flow-resistive loads in young adults: stimulus magnitude effects

Event-related potentials were recorded to brief presentations of four levels of inspiratory flow-resistive loads in young adults. We labeled the loads according to the level of resistance they provided subjectively: sub-threshold (0.34 cmH 2O/l per s), near-threshold (4.01 cmH 2O/l per s), intermediate (10.4 cmH 2O/l per s), and near-occlusion (57.5 cmH 2O/l per s). No discernible ERPs were elicited by the undetected, sub-threshold stimulus but late components of the ERP (P2, N2, and P3) were observed to each of the three larger stimuli. They were related, in part, to behavioral judgments obtained during the stimulus periods. Both the latency and amplitude of the ERP components varied systematically as a function of stimulus magnitude, in a manner comparable to that observed in ERP paradigms using auditory and visual stimuli. Thus, the data show that event-related potentials to breathing are sensitive to physiologic effects of resistive loads present at the onset of inspiration. Respiratory ERPs may be used to infer sensory and perceptual responses to increases in airflow resistance and, accordingly, may relate to the perception of airflow obstruction in patient populations.

Painfulness decreases the discriminability of electric shock.

Two experiments were designed to investigate the relation between the reported painfulness and the discriminability of pairs of electric shocks for which the ratio between the higher and the lower intensity was held constant. In both experiments, subjects first gave category ratings of the painfulness of single shocks in the range 40 to 4.8 mA. Then, in a discrimination experiment, they were required to identify the stronger of a pair of intensities presented in succession. The proportion of correct responses (Experiment 1) or the proportion of area under the receiver operating characteristic (Experiment 2) increased between a low-intensity pairing and a medium-intensity pairing and decreased between a medium-intensity pairing and a high-intensity pairing for subjects who rated the highest intensities as strongly painful. Subjects who gave moderate- or weak-pain ratings for the high-intensity shocks showed no significant increase or decrease in accuracy between the medium- and high-intensity pairings. Time-order errors were observed in Experiment 1. The proportion of trials on which the second stimulus of the pair was identified as the stronger increased monotonically as a function of stimulus magnitude. The results are discussed in the context of psychological assessment of analgesic procedures.

Errata: Validation of an Indicator of Mammalian Retinal Receptor Response: Density of Stain as a Function of Stimulus Magnitude

Errata: Validation of an Indicator of Mammalian Retinal Receptor Response: Density of Stain as a Function of Stimulus Magnitude

Validation of an indicator of mammalian retinal receptor response: density of stain as a function of stimulus magnitude.

A bipartite field (retinal irradiance ratio 2:1 on the two sides) was imaged on the retina of an albino rat. Following exposure to the visual stimulus, the retina was dissected from the eye and placed in an incubation medium which selectively stains the ellipsoid portion of photoreceptors which have been exposed to light. In this study, the optical density of stain was measured as a function of stimulus magnitude. It was shown that the density of stain increased with increasing retinal irradiance over the range of values tested. The indicator system tended to underestimate differences in stimulus magnitude, and showed evidence of approaching an asymptote at higher stimulus levels. Many technical problems encountered in this experiment made this a difficult exercise.

Parameters of Vowel Perception

Psychophysical scales are determined for the amplitude, duration, and fundamental frequency parameters of vowels. Numerical estimates of vowel loudness and of vowel duration grow as a power function of their respective parameter values, while estimates of pitch are a logarithmic function of fundamental frequency. A given change in amplitude, duration, or fundamental frequency of a vowel appears greater to the speaker than to a listener; in other words, autophonic scales of vowel parameters grow more rapidly as a function of stimulus magnitude than do reception scales. When a subject is instructed to match his vocal response to a vowel stimulus, autophonic and reception scales of vowel perception predict the parameters of echoic responding. The matching function for each stimulus parameter shows some influence of the other parameters; the largest effect is the increase in response pitch associated with an increase in stimulus amplitude. This interaction is predicted quantitatively from a simplified analysis of the mechanics of the glottal source and from an empirical determination of pitch-amplitude relations in free responding.