Magnitude production and magnitude estimation of taste intensity

Magnitude productions of sodium chloride (salty), quinine hydrochloride (bitter), and sucrose (sweet) yielded steeper psychophysical functions than those obtained with magnitude estimation. Hydrochloric acid (sour) produced the opposite effect. The results are discussed with respect to previous findings in taste intensity scaling and to general psychophysical considerations.     

Examining auditory kappa effects through manipulating intensity differences between sequential tones

The auditory kappa effect is a tendency to base the perceived duration of an inter-onset interval (IOI) separating two sequentially presented sounds on the degree of relative pitch distance separating them. Previous research has found that the degree of frequency discrepancy between tones extends the subjective duration of the IOI. In Experiment 1, auditory kappa effects for sound intensity were tested using a three-tone, AXB paradigm (where the intensity of tone X was shifted to be closer to either Tone A or B). Tones closer in intensity level were perceived as occurring closer in time, evidence of an auditory-intensity kappa effect. In Experiments 2 and 3, the auditory motion hypothesis was tested by preceding AXB patterns with null intensity and coherent intensity context sequences, respectively. The auditory motion hypothesis predicts that coherent sequences should enhance the perception of motion and increase the strength of kappa effects. In this study, the presence of context sequences reduced kappa effect strength regardless of the properties of the context tones.     

Hearing threshold shift during auditory magnitude estimation.

The purpose of the present experiment was to determine the extent of hearing threshold shift that may occur during an auditory magnitude-estimation task involving stimulus intensities as great as 80 dB sensation level. Also, possible influences of hearing threshold shift on numerical magnitude-estimation responses and magnitude-function slopes were investigated. Results indicated that hearing threshold shift was insignificant (1-2 dB). Consistent small increases in numerical magnitude responses were observed on a magnitude-estimation task where hearing thresholds were retested between stimulus presentations versus a magnitude-estimation task where hearing thresholds were not retested. The stability of auditory magnitude functions across different conditions in the current investigation was in agreement with vibrotactile magnitude-scaling behavior observed by Fucci, et al. in 1989 and 1991. The over-all results supported the concept of an absolute, internal sensory-scaling mechanism being operable during magnitude estimation of auditory stimuli as discussed by Zwislocki and Goodman in 1980.     

Intertrial interval and sequential effects in magnitude scaling.

The intertrial interval (ITI) was varied within subjects in magnitude estimation and cross-modality matching experiments. Fits of a recently proposed time series regression model show that the influence of the previous stimulus intensity on the current response decreases when the ITI is increased. The results can be interpreted as showing that an assimilative or additive perceptual or memory effect decreases with an increase in ITI. Fits of an earlier model, on the other hand, suggest that the influence of the previous stimulus intensity increases with an increase in ITI, which is counter to expectations. The new regression model (a) provides a simple explanation for the counterintuitive results obtained with the earlier model, (b) shows that assimilation in perception or memory can appear as contrast, and (c) reduces to a simpler model for longer ITIs.     

Magnitude estimation and magnitude production: stimulus frequency effects on magnitudes of lingual vibrotactile sensation

The methods of magnitude estimation and magnitude production were employed to investigate the effects of stimulus frequency on supra-threshold lingual-vibrotactile sensation-magnitude functions. The method of magnitude estimation was used to obtain numerical judgments of sensation magnitudes for nine stimulus intensities presented to the anterior dorsum of the tongue. The vibrotactile stimulus frequencies employed for 10 subjects (M age = 21.1 yr.) were 100, 250, and 400 Hz. The numerical responses obtained during the magnitude-estimation task were in turn used as stimuli to obtain magnitude-production values for the same three vibrotactile stimulus frequencies. The results appeared to present two suggestions. First, the effects of stimulus frequency on lingual vibrotactile-sensation magnitudes may be dependent on the psychophysical method used in any particular experiment. Second, lingual-vibrotactile magnitude-estimation scales may demonstrate asymptotic growth functions above about 25 dB sensation level. The limitation in the growth of sensation magnitude occurred for all three vibrotactile stimulus frequencies employed.     

Effects of exposure to psychophysical scaling on lingual vibrotactile magnitude estimation and magnitude production

The purpose of the present study was to determine if the results obtained by the scaling methods of magnitude estimation and magnitude production could be influenced by providing subjects with prior exposure to psychophysical scaling in the form of magnitude estimation or magnitude production. Group 1 (n = 10, Mage = 21.1 yr.) performed lingual vibrotactile-magnitude estimation followed by lingual vibrotactile magnitude production. Group 2 (n = 10, Mage = 19.7 yr.) performed lingual vibrotactile-magnitude production (using the magnitude-estimation responses provided by Group 1), followed by lingual vibrotactile-magnitude estimation. For the magnitude estimations there was no over-all statistically significant difference between the two groups, but there was for the magnitude-production values. Magnitude-estimation scaling was apparently not influenced by prior exposure to magnitude production, while magnitude-production scaling was influenced by prior exposure to magnitude estimation. The results are discussed in terms of how subjective scaling behavior in psychophysical experimentation may be influenced by the interaction between an absolute internal scaling mechanism and parameters set by the experimenter, such as scaling method and range of stimulus intensity.     

Effect of auditory masking on lingual vibrotactile thresholds and magnitude estimation scaling responses

Auditory masking has become a frequently employed part of the procedure used in vibrotactile research. Research investigating the effect of auditory masking on lingual vibrotactile thresholds of sensitivity has shown that there is little difference between lingual vibrotactile thresholds under masking and no masking conditions. The purpose of the present study was to extend the investigation of the effect of auditory masking to include lingual vibrotactile suprathreshold scaling responses. 20 young adult subjects of mean age 19 yr. completed lingual vibrotactile-threshold and magnitude-estimation scaling tasks under conditions of bilateral auditory masking and no masking. Similar lingual vibrotactile-threshold values and magnitude-estimation power-function exponents for the conditions of masking and no masking were noted.     

Variability and sequential effects in cross-modality matching of area and loudness

Individual subjects' performance was examined for cross-modality matching (CMM) of loudness to visual area, as well as for magnitude estimation (ME) of the component continua. Average exponents of power functions relating response magnitude to stimulus intensity were .73 for area, .20 for loudness, and 2.44 for CMM. Predictions of the CMM exponent based on ME were higher than the empirical values, whereas more accurate predictions were made from magnitude production exponents obtained in a previous study. Sequential dependencies were assessed by comparing the response on trial n to the response on trial n--1. The coefficient of variation of the response ratio Rn/Rn-1 was systematically related to the stimulus ratio Sn/Sn-1 for both area and loudness. The coefficient was lowest for ratios near 1 and increased for larger or smaller values. For CMM, the coefficient of variation appeared to be independent of stimulus ratios. The correlation between log Rn and log Rn-1 was also related to Sn/Sn-1 for both ME and CMM. The correlation was highest when Sn/Sn-1 was 1 and dropped to 0 with increasing stimulus separation, but CMM yielded a shallower function than ME.     

Perceived numerosity: A comparison of magnitude production,magnitude estimation,and discrimination judgments

In previous studies, modalities with a higher Weber fraction have tended to have a lower power-function exponent. Within a modality, however, the Weber fraction and power-function exponent for individual subjects were unrelated, and the present study largely confirms this finding for the numerosity dimension. More important than discriminability in the judgment of numerosity were cognitive factors. A single feedback trial considerably reduced intersubject variability on the magnitude-estimation exponent, although it failed to eliminate individual differences completely (precue and postcue exponents correlated signigicantly, r=+.50). Intrasubject variability, by contrast, seemingly did not involve the underlying exponent. As in previous studies, numerosity generally was underestimated and the power-function exponent was 1.08 for magnitude production and .80 for precue magnitude estimation. Contrary to previous results, however, males and females did not differ in exponent, perhaps because the present procedure allowed self-selection of individuals more interested in numerosity tasks.     

Contextual and sequential effects on judgments of sweetness intensity

Presenting stimuli from skewed concentration distributions affects mean responses on category scales. However, if the number of categories on the response scale is increased, the degree of separation between the mean responses obtained for a positively as opposed to a negatively skewed concentration distribution diminishes. The present study investigates the effect of skewed concentration distributions upon ratings on a line scale and compares it to the context effect found for a 7-point category scale. In addition, sequential dependencies between consecutive stimuli and responses are investigated in order to assess their relevance in tasteintensity scaling studies. The context effects are similar for the 7-point category scale and for the line scale. The analyses of sequential effects show that both preceding responses and preceding stimuli affect current responses. However, since these two factors work in opposite directions, only a small contrast effect from the previous stimulus is significant in an overall analysis. The present study shows that even though the overall sequential effects between consecutive stimuli and responses are small, the effect of experimental context may be considerable. Since subjective context is established at the beginning of a session and sequential dependencies operate throughout the whole session, it is argued that contextual and sequential effects are only indirectly related.     

Pervasiveness and magnitude of context effects: evidence for the relativity of absolute magnitude estimation

To test the assertion that absolute magnitude estimation serves to minimize context effects, two experiments were conducted in which area stimuli were judged under differing conditions. In Experiment 1, four groups of subjects made magnitude estimations of triangles ranging in area from 1.5 to 3,072 cm2. No standard or modulus was used, and instructions were similar to those used in absolute magnitude estimation experiments. Each group first judged a different subrange of the stimuli (1.5-24; 48-768; 6-96; or 192-3,072 cm2) before making judgments of the remaining stimuli. In Experiment 2, two groups of subjects made magnitude estimations of triangles ranging in area from 1.5 to 12,288 cm2, with each group first judging a different subrange of stimuli (1.5-24 cm2 or 768-12,288 cm2). The design and instructions were virtually identical to those used in absolute magnitude estimation experiments. Our results indicate that the wording of the instructions is not crucial and that judgments are influenced in two ways that are not predicted by proponents of absolute magnitude estimation. First, the power functions fit to the initially presented subranges (e.g., 1.5-24 cm2), which were judged without contextual effects produced by previously presented stimuli, were inconsistent with one another. Second, judgments of the remaining stimuli were influenced by the subrange of stimuli judged initially. The prevalence of context effects in both experiments, in spite of instructional differences, suggests that although one should avoid using a standard and modulus, there is little else to be gained by adopting the absolute magnitude estimation procedure.     

Stability of individual loudness functions obtained by magnitude estimation and production

A correlational analysis of individual magnitude estimation and production exponents at the same frequency was perfor.med, as well as an analysis of individual exponents produced in different sessions by the same procedure across frequency(250, 1, 000, and 3, 000 Hz). Taken together, results show, first, that individual exponent differences do not decrease by counterbalancing magnitude estimation with magnitude production, and, second, that individual exponent differences remain stable over time despite changes in stimulus frequency. Further results disclose that although individual magnitude estimation and production exponents do not necessarily obey the .6 power law, it is possible to predict the slope (exponent) of an equal-sensation function averaged for a group of listeners from individual magnitude estimation and production data. Assuming that individual listeners with sensorineural hearing loss also produce stable and reliable magnitude functions, it is also shown that the slope of the loudness-recruitment function measured by magnitude estimation and production can be predicted for individuals with bilateral losses of long duration. Thus, results obtained in normal and in pathological ears suggest that individual listeners can produce loudness judgments that reveal, albeit indirectly, the input-output characteristic of the auditory system.     

Reliability and magnitude of auditory laterality effects: the influence of attention

Three experiments investigated the effect of attention on the reliability and magnitude of laterality effects in a dichotic listening task. In Experiment 1, 40 undergraduate students were randomly assigned to either a free-recall or focused-attention condition. In Experiment 2, 40 undergraduate students completed a dichotic listening task with exogenous cueing. They were randomly assigned to either a 150-ms stimulus onset asynchrony (SOA) or a 450-ms SOA condition. In Experiment 3, 20 participants completed a task where the SOA for the exogenous cue was randomized on a trial to trial basis. Results indicated that focused attention increased the magnitude of the laterality effect. Contrary to predictions, this finding was not due to reduced variability in the focused-attention task compared to the free-recall task. In addition, a cueing tone was only effective at directing attention in Experiment 3. Specifically, a significant right ear advantage observed at the 150-ms SOA was reduced at the 450-ms SOA. It appears that, in Experiment 3, the tone was effective at controlling attention because it reduced the systematic bias that has been suggested to account for the laterality effects observed in dichotic tasks.     

Contextual and sequential effects on judgments of sweetness intensity.

Presenting stimuli from skewed concentration distributions affects mean responses on category scales. However, if the number of categories on the response scale is increased, the degree of separation between the mean responses obtained for a positively as opposed to a negatively skewed concentration distribution diminishes. The present study investigates the effect of skewed concentration distributions upon ratings on a line scale and compares it to the context effect found for a 7-point category scale. In addition, sequential dependencies between consecutive stimuli and responses are investigated in order to assess their relevance in taste-intensity scaling studies. The context effects are similar for the 7-point category scale and for the line scale. The analyses of sequential effects show that both preceding responses and preceding stimuli affect current responses. However, since these two factors work in opposite directions, only a small contrast effect from the previous stimulus is significant in an overall analysis. The present study shows that even though the overall sequential effects between consecutive stimuli and responses are small, the effect of experimental context may be considerable. Since subjective context is established at the beginning of a session and sequential dependencies operate throughout the whole session, it is argued that contextual and sequential effects are only indirectly related.     

Bias effects on magnitude and ratio estimation power function exponents

A bias model of relative judgment was used to derive a ratio estimation (RE) power function, and its effectiveness in providing estimates of exponents free of the effects of standards was evaluated. The RE bias model was compared with the simple RE power function that ignores bias. Results showed that when bias was not taken into account, estimates of exponents exhibited the usual effects of standards observed in previous research. However, the introduction of bias parameters into the RE power function virtually eliminated these effects. Exponents calculated from "equal-range segments" (e.g., low stimulus range vs. high stimulus range) judged by magnitude estimation (ME) were examined: the effects of equal-range segments on exponents were much stronger for ME than standards were for RE, using the bias model.     

The influence of category membership of stimuli on sequential effects in magnitude judgment

The present study addresses the problem of whether range effects and sequential dependencies are affected by stimulus category membership in the same way. Two sets of squares differing in color were presented to subjects. The subjects were asked to judge them according to size, under two instructions. The separation instruction required them to judge each square solely in relation to its own category. The integration instruction required them to ignore category membership. The results indicated that, under the separation instruction, the range effects, as well as the sequence effects, confined themselves to stimuli of the same category. Under the integration instruction, however, the squares were judged in relation to the range of all the stimuli, and sequential effects were independent of the stimulus category. This parallel trend in the category-specific effects of range and preceding stimuli was found for judgments, as well as for reaction times. The findings are discussed with regard to models of sequential effects.     

Prepulse effects on magnitude estimation of startle-eliciting stimuli and startle responses

The present studies investigated the relationship between prepulse effects on the modification of the brainstem startle reflex and magnitude estimates of startle-eliciting stimuli. In Experiment 1, startle eyeblink responses were elicited in 24 students, half of whom were instructed to estimate the loudness of the startle stimulus (actual intensities of 80, 90, and 100 dB) and half of whom were instructed to estimate the magnitude of their eyeblink. When weak acoustic prepulses preceded the startle-eliciting stimulus, eyeblink amplitude was inhibited, and estimates of response magnitude decreased, but estimates of startle stimulus magnitude decreased only when 100-dB startle stimuli were presented. In Experiment 2, the same startle stimuli were preceded on some trials by a vibrotactile prepulse to the hand. In conditions in which startle amplitude was inhibited, startle stimulus magnitude estimates were not affected. This suggests that the effect of acoustic prepulses on 100-dB startle stimuli in Experiment 1 may have been due to loudness assimilation, an effect independent of the prepulse inhibition of startle responding.     

Stimulus intensity effects on auditory and visual reaction processes.

Literature on the effect of stimulus intensity on reaction processes was reviewed. It was shown that there is no agreement as to whether intensity effects are limited to encoding or whether they are extended to later processing stages. The situation can be characterized as an asymmetry between modalities: vision is consistent with the first alternative and audition with the second.Chronometric analysis was used to bear on the question. It was shown that the effects of visual intensity and foreperiod (FP) are additive in a simple RT situation both for constant and mixed blocks FP. Auditory intensity and FP interact in both simple and two-choice situations. In a control experiment visual intensity and S-R compatibility were found to be additive. The asymmetry was accounted for by auditory alerting, previously discussed by several authors.The framework of stimulus intensity research utilizing RT measures was briefly evaluated.