The intensity-difference limen for 6.5 kHz: an even more severe departure from Weber's law

Intensity-difference limens (DLs) were obtained for tones of 6.5 kHz over levels of 30-90 dB SPL. The tones had Gaussian-shaped envelopes whose duration was expressed as equivalent rectangular duration D, that of a rectangle enclosing the same area as the envelope. D ranged from 0.314 to 30 msec. DL behaviors such as the "severe departure from Weber's law," the "midlevel hump," or the "midduration hump"--that is, a rise in the DL over a range of short durations--were identified using trend analysis. The DL versus level followed a "severe departure" that increased as duration dropped to D approximately 1-2 msec. That midlevel hump then fell with further shortening of the tone pip, producing a mid-duration hump. Materials for this article may be accessed through the Psychonomic Society's Norms, Stimuli, and Data archive, at www.psychonomic.org/archive.     

Infants’ detection of increments in low- and high-frequency noise

A visually reinforced operant paradigm was employed to examine the relationship between the difference limen (DL) for intensity and level of the standard during infancy. In Experiment 1,7-month-old infants and adults detected increments in continuous noise presented via headphones at each of four levels ranging from 28 to 58 dB SPL. Noise stimuli were 2-octave bands centered at either 400 or 4000 Hz, and increments were 10 and 100 msec in duration. Infants’ DLs were significantly larger than those of adult subjects and significantly larger for low- than for high-frequency stimuli. For the high-frequency noise band, infants’ DLs were generally consistent with Weber’s law,remaining essentially constant for standards higher than 28 dB SPL (3 dB SL) for 100-msec increments and 38 dB SPL (13 dB SL) for 10-msec increments. For low-frequency noise, infants’ absolute thresholds were exceptionally high, and sensation levels of the standards were too low to adequately describe the relationship. In Ex-periment 2, 7-month-old infants detected 10- and 100-msec increments in 400-Hz noise stimuli presented in sound field. Infants’ low-frequency DLs were large at low intensities and decreased with increases in level of the standard up to at least 30 dB SL. For both low- and high-frequency noise, the difference between DLs for 10- and 100-msec increments tended to be large at low levels of the standard and to decrease at higher levels. These results suggest that the relationship between the DL and level of the standard varies with both stimulus frequency and duration during infancy. However, stimulus-dependent immaturities in increment detection may be most evident at levels within approximately 30 dB of absolute threshold.     

Auditory temporal order and perceived fusion-nonfusion

A pair of pure-tone sine waves, with the first tone presented randomly to either ear, was presented simultaneously or sequentially. The order of occurrence of the tones (temporal order) and the number of tones perceived (fusion-nonfusion) were judged. Three values of stimulus intensity (40, 55, and 70 dB SPL) and 10 values of stimulus onset asynchrony (SOA; 0, 1, 2, and 4 to 28 msec in 4-msec steps) were varied. Of major importance in this investigation was the relationship between the judgmental tasks of temporal order and fusion-nonfusion. Response time and accuracy were the dependent measures used to assess that relationship. The results of two groups of 10 subjects showed an increase in the percentage of correct nonfusion judgments with increases in stimulus intensity and SOA. For correct judgments of temporal order, no significant intensity or SOA effects were noted. Response time for the fusion-nonfusion task was significantly influenced by both stimulus intensity and SOA. For the response times associated with the temporal order task, intensity was significant. More important to this investigation was the observed Intensity by SOA by Task interaction for response time data. These results suggest a hybrid model, with different processes occurring within different stages of this model.     

Discrimination of time intervals bounded by tone bursts

Trained listeners had to discriminate, in a four-level 2AFC paradigm, the duration of a time interval bounded by pairs of brief tone bursts. The time intervals ranged from 10 to 100 msec. When the tone-burst markers were similar in their intensity (86 dB SPL) and frequency (1 kHz), the just noticeable time difference was found to be monotonically related to the base interval. On the other hand, when the intensity of the first marker was severely attenuated (by 50 dB) or when a large (2-octave) difference was introduced between the frequencies of the two markers, the time discrimination functions became nonmonotonic. A similar, albeit slight, departure from monotonicity was also achieved by making the second marker much longer than the first (300 msec vs. 10 msec). The nonmonotonicity of these time discrimination functions is compared to the well-documented nonmonotonicity that may be observed for voice onset time (VOT) discrimination functions.     

Systematic covariation of the parameters in the near-miss to Weber's law, pointing to a new law

The exponent in the power function modeling of the near-miss to Weber's law is known to depend on several experimental factors, such as tone frequency and the presence or absence of noise. This paper presents data that confirm a theoretical argument that the near-miss exponent also depends on the definition of ‘just-noticeably different’ used empirically. Intensity discrimination data were collected for pure, 1000-Hz tones presented in quiet. Referent sound pressure levels ranged from 40 to 80 dB SPL in 10-dB steps. For each referent, the tone judged louder than the referent with probability equal to ν was determined, with ν ranging from 0.16 to 0.84. It was found that the power function exponent decreases monotonically with ν. Moreover, it was found that the two power law parameters co-vary systematically with ν, implying a submodel that has an interesting fixed-point property.     

Reaction time and visual brightness: within-subject correlations.

An experiment was conducted to compare visual reaction time and visual brightness within the same subjects. Simple reaction times and magnitude estimates of brightness were obtained in response to 1000-msec. flashes of 60.7, 67.5, 76.4, 85.1, and 93.4 dB re 10(-10)L white light. The relationship between reaction time and stimulus intensity was best described by a negative logarithmic function, while the relationship between magnitude estimates of brightness and stimulus intensity was best described by a power function. Linear correlations between reaction times and magnitude estimates indicated that visual reaction time and brightness are not proportional within all subjects. Previous reports of proportionality between these two measures were discussed as possibly being the result of inappropriate cross-experiment comparisons.     

Auditory discrimination of anisochrony: influence of the tempo and musical backgrounds of listeners

This study explored the influence of several factors, physical and human, on anisochrony's thresholds measured with an adaptive two alternative forced choice paradigm. The effect of the number and duration of sounds on anisochrony discrimination was tested in the first experiment as well as potential interactions between each of these factors and tempo. In the second experiment, the tempo or the inter onset interval (IOI) was varied systematically between 80 and 1000 ms. The results showed that just noticeable differences increase linearly and proportionally with IOI in accordance with Weber's law except for quickest tempo (IOI of 80 ms). The third experiment investigated the role of musical training on anisochrony thresholds obtained for different IOI. It focused on differential effects of musical experiences by comparing non-musicians, instrumentalists, and percussionists thresholds. The results of the present study replicated the findings of previous experiments regarding the adequacy of Weber's law for slow rhythm and provided evidence for its departure for fast tempos. Moreover, thresholds from percussionists seem distinguishable from the ones of other listeners by their highest sensitivity to temporal shifts suggesting therefore the necessity to control the nature of musical experiences. The results are discussed according to current models of time perception.     

A study of the near-miss involving Weber’s law and pure-tone intensity discrimination

A study of pure-tone intensity discrimination is presented in which amplitude changes are detected in 1000 Hz tone bursts 15–20 msec in duration. The masking function (log detectable increment vs log background intensity) is found to have a slope of 9/10 when calculations are carried out via energy measurements. This near-miss to Weber’s law is in agreement with other data reported in the literature. The masking slope proves to be essentially independent of stimulus duration between 15 msec and 1.5 sec. Our stable slope parameter is interpreted as a detectability restriction generated by “mass-flow” phenomena in the auditory channel. These phenomena are thought to be similar to the fluctuations accompanying a noisy or turbulent stream of events. Pure-tone intensity discrimination is then analyzed as a special case of energy detection.     

Auditory apparent motion in the free field: the effects of stimulus duration and separation.

The effects of stimulus duration and spatial separation on the illusion of apparent motion in the auditory modality were examined. Two narrow-band noise sources (40 dB, A-weighted) were presented through speakers separated in space by 2.5 degrees, 5 degrees, or 10 degrees, centered about the subject's midline. The duration of each stimulus was 5, 10, or 50 msec. On each trial, the sound pair was temporally separated by 1 of 10 interstimulus onset intervals (ISOIs): 0, 2, 4, 6, 8, 10, 15, 20, 50, or 70 msec. Five subjects were tested in nine trial block; each block represented a particular spatial-separation-duration combination. Within a trial block, each ISOI was presented 30 times each, in random order. Subjects were instructed to listen to the stimulus sequence and classify their perception of the sound into one of five categories: single sound, simultaneous sounds, continuous motion, broken motion, or successive sounds. Each subject was also required to identify the location of the first-occurring stimulus (left or right). The percentage of continuous-motion responses was significantly affected by the ISOI [F(9,36) = 5.67, p less than .001], the duration x ISOI interaction [F(18,72) = 3.54, p less than .0001], and the separation x duration x ISOI interaction [F(36,144) = 1.51, p less than .05]. The results indicate that a minimum duration is required for the perception of auditory apparent motion. Little or no motion was reported at durations of 10 msec or less. At a duration of 50 msec, motion was reported most often for ISOIs of 20-50 msec.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intensity effects of the auditory evoked brain response to stimulus onset and cessation

Average evoked brain responses (EBR) to the onset (ON) and cessation (OFF) of 1-kHz pure-tone stimuli were computed from human scalp recordings. Stimuli of 2,000 msec duration were presented binaurally at 10 intensity levels. The waveform of the OFF EBR is similar to the ON EBR. The ON response is in general larger than the OFF response. Comparable ON and OFF amplitude response measures are both sensitive to changes in stimulus intensity which may be fit by a linear function. Significant differences in slope between ON and OFF amplitude intensity functions were demonstrated, which suggests different physiological systems for these responses.     

Temporal reproduction

A signal appeared for a certain time period. After the period elapsed, pigeons had to begin and complete a sequence of 15 responses in a time window ranging from the signal duration to 50% longer. Sessions involved as many as 10 different signal durations occurring in a random sequence. The times produced by pigeons often were in the same ranges as those that have been found with adult human subjects. The average times were described equally well as linear or power functions of signal duration. However, instead of the overestimation of durations usually found when animals have timed the duration of antecedent stimuli, the linear functions suggested that the pigeons underestimated the durations of their own behavior. The birds showing the strongest control when the conditions involved eight or 10 different duration requirements revealed the constant coefficients of variation that support Weber's law and scalar timing theory. Scalar timing in temporal differentiation appears to depend on non-ambiguous information about the duration required for reinforcement and on a high degree of sensitivity to the duration requirement.     

The Perceptual Centre of a Stimulus as the Cue for Synchronization to a Metronome: Evidence from Asynchronies

In tasks where subjects are required to tap in synchrony to a sequence of evenly spaced uniform auditory stimuli (a metronome), tap onsets typically tend to anticipate the metronome's stimulus onsets. We investigated this phenomenon, called “negative asynchrony”, as a function of (1) the duration of the stimuli (1 or 2, 50, 100, and 300 msec), (2) the rise time of the stimuli (0%, 40%, and 80% of stimulus duration), and (3) the interstimulus onset interval duration (500, 700, and 900 msec). The results from three experiments with 28 different subjects showed a significant reduction of the negative asynchrony with longer stimulus durations, and the reduction was not significantly affected by the tempo of the stimulus sequence. Also, a prolongation of the rise time of the stimuli caused an analogous reduction of the negative asynchrony. Findings were taken to suggest that subjects use the perceptual centre rather than physical onset of stimulus as the cue with which to synchronize     

Auditory evoked brain responses: Comparison of ON and OFF responses at long and short durations

Average evoked brain responses (EBRs) to three durations of one kilohertz pure-tone stimuli were computed from human scalp recordings. Stimuli of 25, 75, and 2,000 msec duration were each presented binaurally at each of eight equally spaced intensity levels, ranging from 58 to 86 dB SPL. EBRs computed immediately following presentation, and immediately following removal of the 2,000-msec-duration stimulus result in ON and OFF responses, respectively. EBRs computed immediately following presentation of the 25- and 75-msec-duration stimuli appear to be the result of the sum of separate responses to stimulus onset and offset. Computer-dissected ON and OFF EBRs to short-duration stimuli are very similar in waveform and amplitude to the responses evoked by the onset and offset, respectively, of the 2,000-msec duration stimulus. Dissected ON and OFF responses demonstrate linear amplitude-intensity functions in amplitude ranges similar to respective ON and OFF responses to 2,000-msec stimulation. The data suggest that ON and OFF responses are mediated by independent physiological mechanisms.     

THE INFLUENCE OF AUDITORY STIMULUS INTENSITY ON APPARENT DURATION

B erglund , B., B erglund , U., E kman , G. & F rankenhaeuser , M. The influence of auditory stimulus intensity on apparent duration. Scand J. Psychol ., 1969, 10 21–26.— apparent duration of an auditory signal of 1000 C/S was measured by the method of magnitude estimation. Ten different stimulus intensities ranging from 57 to 104 dB were used in combination with three different durations: 50, 250, and 500 msec. The results showed that the apparent duration of the signal grew as a logarithmic function of stimulus intensity. These results are consistent with the hypothesis relating apparent duration to activation level as well as with results of similar experiments involving electrical and vibrotactile stimulation.     

Information processing of letter and word pairs as a function of on and off times

The present study seeks to extend a provisional model of visual information processing with sequential inputs currently under development, employing a computer-based cathode-ray tube display system. Letter and word pairs were presented for 28 different on-off time combinations with on times ranging from 5 msec to 50 msec and off times ranging from 1 msec to 125 msec. The results suggest that both on, off, and total processing times affect per cent correct detections, and that while a gradual increase in per cent correct detections occurs up to about 50 msec of total processing time, a marked discontinuity appears to occur approximately between 50 and 60 msec of total processing time, with per cent correct detections jumping abruptly from about 40% correct detections to about 90% correct detections over a total processing time span of only 10 msec.     

Bloch’s law and a Poisson counting model for simple reaction time to light

A series of three experiments was conducted with identical design as an earlier series (Hildreth, 1973). Its purpose was (1) to determine whether Bloch’s law holds for simple reaction time (RT) to still lower intensity visual stimuli, and (2) to provide data for testing a stochastic generalization of the temporal integration model (TI-ED) reported earlier. RT means were found to agree with Bloch’s law for durations below 48 msec. By a statistical test, Bloch’s law was shown to hold for both means and standard deviations below about 65 msec. Latency statistics—means and standard deviations—were predicted by a Poisson process counting model. This model assumes that a number of identical, parallel Poisson processes, activated by light, with pulse interarrival times decreasing with light intensity, trigger light detection when a critical number of pulses arrive at a counting center. For the intensities investigated, both the estimated number of Poisson processes and critical number of pulses required for detection range between 8 and 13. The model predicts the Broca-Sulzer effect for mean RTs which is observed in several of these experiments.     

Auditory apparent motion in the free field: The effects of stimulus duration and separation

The effects of stimulus duration and spatial separation on the illusion of apparent motion in the auditory modality were examined. Two narrow-band noise sources (40 dB, A-weighted) were presented through speakers separated in space by 2.5°, 5°, or 100, centered about the subject’s midline. The duration of each stimulus was 5, 10, or 50 msec. On each trial, the sound pair was temporally separated by 1 of 10 interstimulus onset intervals (ISOIs): 0, 2, 4, 6, 8, 10, 15, 20, 50, or 70 msec. Five subjects were tested in nine trial blocks; each block represented a particular spatial-separation-duration combination. Within a trial block, each ISOI was presented 30 times each, in random order. Subjects were instructed to listen to the stimulus sequence and classify their perception of the sound into one of five categories: single sound, simultaneous sounds, continuous motion, broken motion, or successive sounds. Each subject was also required to identify the location of the first-occurring stimulus (left or right). The percentage of continuous-motion responses was significantly affected by the ISOI [F(9,36) = 5.67,p < .001], the duration × ISOI interaction [F(18,72) = 3.54,p < .0001], and the separation × duration × ISOI interaction [F(36,144) = 1.51,p < .05]. The results indicate that a minimum duration is required for the perception of auditory apparent motion. Little or no motion was reported at durations of 10 msec or less. At a duration of 50 msec, motion was reported most often for ISOIs of 20–50 msec. The effect of separation appeared to be limited to durations and-ISOIs during which little motion was perceived.     

Rapid Word Recognition as a Measure of Word-Level Automaticity and its Relation to Other Measures of Reading

The present study investigated the relationship between rapid recognition of individual words (Word Recognition Test) and two measures of contextual reading: (1) grade-level Passage Reading Test (IRI passage) and (2) performance on standardized STAR Reading Test. To estabilish if time of presentation on the word recognition test was a factor in predicting contextual reading performance, four computerized presentation times were used: 300 msec, 650 msec, 1000 msec, adn 2000 msec. Regression analyses revealed that, for both third- and fourth-grade students, there was evidence that presentation times of less than 1 second better approximated performance on the two contextual reading measures.     

Reaction time to the onset and offset of electrocutaneous stimuli as a function of rise and decay time

Reaction times were obtained to the onset and offset of 70-cps electrocutaneous signals of five rise and decay times and five intensity levels. The results show that both onset and offset RTs increase linearly with increased rise and decay times. With fast rates of rise or decay, the onset produces faster RTs than the cessation of stimulation. The opposite effect is found when long rise and decay times are used. Interpretations of these results are given in terms of neural adaptation and accommodation.     

Reaction time to the onset and offset of electrocutaneous stimuli as a function of rise and decay time

Reaction times were obtained to the onset and offset of 70-cps electrocutaneous signals of five rise and decay times and five intensity levels. The results show that both onset and offset RTs increase linearly with increased rise and decay times. With fast rates of rise or decay, the onset produces faster RTs than the cessation of stimulation. The opposite effect is found when long rise and decay times are used. Interpretations of these results are given in terms of neural adaptation and accommodation.