Range and regression, loudness scales, and loudness processing: Toward a context-bound psychophysics.

How does context affect basic processes of sensory integration and the implicit psychophysical scales that underlie those processes? Five experiments examined how stimulus range and response regression determine characteristics of (1) psychophysical scales for loudness and (2) 3 kinds of intensity summation (binaural loudness summation, summation of loudness between tones widely spaced in frequency, and temporal loudness summation). Context affected the overt loudness scales in that smaller power-function exponents characterized larger vs smaller range of stimulation and characterized magnitude estimation vs magnitude production. More important, however, context simultaneously affected the degree of loudness integration as measured in terms of matching stimulus levels. Thus, stimulus range and scaling procedure influence not only overt response scales but measures of underlying intensity processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The processing of duration and intensity cues to prominence

This paper presents results from two experiments designed to show how duration and intensity are processed during speech perception. Duration and intensity are two physical dimensions which are known to interact psychoacoustically in the perception of both length (a term that will be used for perceived duration) and loudness. The first experiment, a selective attention task, shows that length and loudness are processed as a unit [integrally, in the terms of Garner, The Processing of Information and Structure (Erlbaum, Potomac, MD, 1974)], but that the integrality is asymmetric: Extracting length information appears to be easier than extracting loudness information. The results of the first experiment make the prediction that listeners would not use loudness by itself in making prominence judgments, since the extraction of loudness in the presence of duration variation appears to require a (relatively) high processing load. The second experiment, a traditional trading relation experiment in which duration and intensity were varied orthogonally, appears to bear out this prediction. Listeners' responses were predicted from computed measures of length and loudness in a linear multiple regression analysis. Results show a negligible independent contribution of loudness to listeners' responses. Listeners' behavior is best predicted by computed measures of length.     

Models for biases in judging sensory magnitude.

Category ratings and magnitude judgments are affected by 4 range biases, the centering bias, the stimulus and response equalizing biases, and the contraction bias; by 3 nonlinear biases, the local contraction bias, the stimulus spacing bias, and the logarithmic bias; and by bias from transfer. Models of the biases are described. The biases are most marked in sensory dimensions that students are not taught to handle, such as loudness and brightness. Avoiding all the biases requires exceedingly rigorous investigations. (77 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification variability as a measure of loudness: An application to gender differences.

It is well known that discrimination response variability increases with stimulus intensity, closely related to Weber's Law. It is also an axiom that sensation magnitude increases with stimulus intensity. Following earlier researchers such as Thurstone, Garner, and Durlach and Braida, we explored a new method of exploiting these relationships to estimate the power function exponent relating sound pressure level to loudness, using the accuracy with which listeners could identify the intensity of pure tones. The log standard deviation of the normally distributed identification errors increases linearly with stimulus range in decibels, and the slope, a, of the regression is proportional to the loudness exponent, n. Interestingly, in a demonstration experiment, the loudness exponent estimated in this way is greater for females than for males. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A dynamic theory of proportional judgment: Context and judgment of length, heaviness, and roughness.

Ss judged the length of lines, the heaviness of weights, or the roughness of sandpaper in 2 conditions. In one condition, they were instructed to make all their judgments relative to a long-term reference point, which consisted of a reference response and sensation. In the other condition, they were told to use a short-term reference point, namely, the response and sensation of the previous trial. A dynamic model of proportional judgment (L. T. DeCarlo; see record 1993-12129-001) predicts that the autocorrelation of successive responses will be larger for the latter instructions. This prediction was confirmed for the 3 continua. In addition, fits of a recently proposed dynamic regression model show that there is little or no effect of the previous stimulus intensity on the current response, whereas the results for an earlier model suggest a large contrast effect. The theory and experiments provide insight into judgmental and sensory processes in magnitude scaling. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison requirements and attention in identical-nonidentical stimulus discriminations.

Perceptual matching data show several puzzling effects. Particularly problematic are the disparities between the processing rates for same and different stimuli—the fast–same effect—and between the processing rates for two same–different judgment tasks that are related as mirror images—the task effect. Current models have difficulty accounting simultaneously for both effects. Central to these models is a stimulus comparison process that derives relative judgments of sameness and difference from tests of the congruence of stimulus representations. A contrasting view holds that same–different judgments can be modeled as absolute, rather than relative, judgments. This latter view is shown to be supported by experimental data. Reaction times (RTs) for judgments of identical letter strings increase with string length at the same rate whether judgments are based on all the information in the strings or just the information in a single pair of component letters. The data show that stimulus comparisons of the sort described by previous models are not involved in these judgments. An attentional model accounts for the data and for the fast–same and task effects as well. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in loudness processing and loudness scales.

Assessed parameters of the psychophysical function for loudness (a 1,000-Hz tone) for 9 undergraduates in 3 experiments: binaural loudness summation, temporal loudness summation, and judgments of loudness intervals. Findings reveal that the loudness scales that underlay the additive binaural summation closely approximated S. S. Stevens's (see record 1957-02311-001) sone scale but were nonlinearly related to the scales that underlay the subtractive interval judgments, the latter approximating W. R. Garner's (see record 1954-07051-001) lambda scale. Interindividual differences in temporal summation were unrelated to differences in scaling performance or in binaural summation. Although the exponents of magnitude-estimation functions and the exponents underlying interval judgments varied considerably from S to S, exponents computed on the basis of underlying binaural summation varied less. Results suggest that interindividual variation in the exponent of magnitude-estimation functions largely reflects differences in the ways that Ss use numbers to describe loudness and that the sensory representations of loudness are fairly uniform among people with normal hearing. The magnitude of individual variation in temporal summation seems at least as great as the magnitude of the variation in the underlying loudness scale. (78 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Absolute Judgments Are Relative: A Reinterpretation of Some Psychophysical Ideas.

A central theoretical assumption in classical psychophysics is that people judge the intensities of stimulus elements; for example, observers directly report the loudness of a tone or the intensity of a shock. A methodological assumption in classical psychophysics is that averaged data demonstrate this theoretical view. It is shown in this article that both assumptions are wrong and that the psychophysical laws of Weber, Fechner, and Stevens are not general. Rather, psychophysical judgments are made in relation to contexts and memories, measures of which provide new information about psychophysical judgments and new understandings of channel capacity, the local-global distinction, and the source of noise in signal detection theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Loudness change in response to dynamic acoustic intensity.

Three experiments investigate psychological, methodological, and domain-specific characteristics of loudness change in response to sounds that continuously increase in intensity (up-ramps), relative to sounds that decrease (down-ramps). Timbre (vowel, violin), layer (monotone, chord), and duration (1.8 s, 3.6 s) were manipulated in Experiment 1. Participants judged global loudness change between pairs of spectrally identical up-ramps and down-ramps. It was hypothesized that loudness change is overestimated in up-ramps, relative to down-ramps, using simple speech and musical stimuli. The hypothesis was supported and the proportion of up-ramp overestimation increased with stimulus duration. Experiment 2 investigated recency and a bias for end-levels by presenting paired dynamic stimuli with equivalent end-levels and steady-state controls. Experiment 3 used single stimulus presentations, removing artifacts associated with paired stimuli. Perceptual overestimation of loudness change is influenced by (1) intensity region of the dynamic stimulus; (2) differences in stimulus end-level; (3) order in which paired items are presented; and (4) duration of each item. When methodological artifacts are controlled, overestimation of loudness change in response to up-ramps remains. The relative influence of cognitive and sensory mechanisms is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Ratio" and "difference" judgments for length, area, and volume: Are there two classes of sensory continua?

Subjects were required to judge ratios and differences of (a) line length for pairs of lines, (b) area for pairs of squares, and (c) volume for pairs of cubes. Nonmetric analyses of these judgments indicated that all subjects were able to make consistent ratio judgments for all three continua. Many of the subjects, when asked to judge subjective differences, however, performed as if they were judging subjective ratios rather than differences. The data for the few subjects who appeared to be judging subjective differences were not consistent across subjects and conditions. Previous studies of ratio and difference judgments of loudness and heaviness, on the other hand, showed the opposite pattern, in that subjects most often behaved as if they were judging sensory differences when asked to judge sensory ratios. We propose that ratio judgments are more natural to perceptual continua along which stimuli are easily "decomposed" into a number of smaller perceptual units. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding loudness by electric stimulation of the auditory nerve

Electric charge has long been hypothesized to be the effective stimulus variable that determines loudness evoked by directly stimulating the auditory nerve. This 'equal-charge, equal-loudness' hypothesis predicts that stimulus amplitude and duration can be traded linearly to produce equal loudness. Loudness sensations from threshold to maximum loudness were measured systematically as a function of stimulus amplitude and duration in cochlear implant listeners. The measured data do not support the equal-charge, equal-loudness hypothesis: an increment in stimulus amplitude produces a significantly louder sensation than the same change in stimulus duration. Instead of the linear equal-charge model, a power-function model successfully predicts the measured data and should be used to encode loudness in electric hearing.     

Parallel memory retrieval in dual-task situations: I. Semantic memory.

Can participants retrieve information about the 2nd of 2 stimuli while they are processing the 1st? Four experiments suggest they can. Reaction times to the 1st stimulus were faster if it came from the same category as the 2nd than if it came from a different category. This category-match effect was observed for letter-digit discrimination (Experiment 1), magnitude and parity judgments about digits (Experiment 2), and lexical decisions (Experiment 3). Experiment 4 showed that the 2nd stimulus could semantically prime the 1st. The category-match effect was observed only when the same task was performed on the 2 stimuli. When the task changed from the Ist stimulus to the 2nd, there was no advantage of a category match. This dependence on task set may explain previous failures to find parallel retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Remembrance of sounds past: Memory and psychophysical scaling.

What is the role of long-term memories of previous stimulus-response mappings, and of previous sensory and perceptual experiences generally, in psychophysical scaling judgments? In each of 4 experiments, subjects made judgments of the loudness of sounds on 3 successive days. Stimulus intensities were drawn randomly from the same set on Days 1 and 3 but from a different set on Day 2. Four different types of psychophysical scaling judgments were studied. The first two methods required completely relative judgment, the last two completely absolute judgment. Data from all methods reveal profound effects of stimulus-response mappings experienced on previous days and immediately previous stimuli and responses on responses to current stimuli. Responses were typically a compromise between absolute and relative judgment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cross-modal additive conjoint structures and psychophysical scale convergence.

I investigated a variety of issues related to the measurement of the magnitude of psychological experience, especially the magnitude of sensations. Different groups of subjects made pair comparisons, magnitude estimations, and category judgments of the "total sensory magnitude" of light and sound stimuli presented conjointly. Another group judged the dissimilarity of pairs of conjoint stimuli. Various axioms, especially double cancellation, were tested on the resulting rank orders of conjoint stimuli. Judgments of the total magnitude of conjoint combinations of sound and light stimuli formed an additive conjoint structure. Dissimilarity judgments gave rise to a closely related lattice structure. Moreover, various scales of the individual attributes (loudness and brightness) calculated from the two types of judgments of the conjoint stimuli displayed substantial convergence, each scale for a given modality being linear with all other scales for that modality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context effects in left-right shape discrimination.

The difficulty of discriminating between left–right orientations of a shape has usually been attributed to symmetrical coding in the brain or to the nature of perceptual learning. However, recent work on the context-dependent nature of the difficulty challenges such explanations and supports a more cognitive approach to the problem. The present work examined the basis for left–right difficulty in the standard two-choice task (stimuli aligned side by side) in children of 3 to 4 years. Experiment 1 found that children who learned the task with the easy, single-stimulus procedure could generalize to the difficult, two-choice task. Subsequent experiments found that the difficulty in learning the two-choice task could not be attributed to the attentional demands of the two stimuli, nor to the use of the second stimulus as a spatial referent for defining orientation. The data suggested that the standard two-choice task is difficult because it promotes the use of two competing orientation judgments. We conclude that the difficulty of left–right judgments lies in the cognitive demands of the task and is to be understood in the same terms as other problems in cognitive development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Immediate memory in sequential tasks.

Factors effecting the memory capacity are basic to understanding sequential tasks. The evidence indicates immediate memory is sometimes subject to decay, but that interference from interpolated items has a much larger effect. Interference effects are particularly great when the S must hold items in store while responding to previously stored material within an ongoing serial task. The ability of S to use time to reorganize the stimuli for storage works against the decay tendency. Only in rare instances does S store a pure representation of the stimulus; rather he must be viewed as an active information handler applying his knowledge of the nature of the stimulus and response to reduce his memory load. (56 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sensory and cognitive components of visual information acquisition.

Describes a theory of visual information acquisition and visual memory. The theory has 2 major components. First, the visual system's initial sensory response to a short-duration, low-contrast stimulus is generated by a linear, low-pass temporal filter that operates on the stimulus's temporal waveform. Second, information is acquired from a stimulus through an independent-sampling process whose sampling rate at time t following stimulus onset is jointly proportional to (1) the magnitude by which the sensory response exceeds some threshold and (2) the proportion of still unacquired information. The theory was successfully tested in 5 variants of a digit recall task in which temporal waveform of the stimulus was systematically manipulated. In a final experiment, the theory simultaneously accounted for performance in detection and identification tasks. Implications for visual information processing, low-contrast detection, and binocular combination of information are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Right hemisphere superiority in visual orientation matching.

"Same" or "different" judgments were made by 22 right-handed college students in 2 orientation matching tasks. In 1 task pairs of lines were presented 4. left or right of fixation. Reaction times for both "same" and "different" judgments were faster if stimulus pairs were presented to the left visual field, indicating superiority of the right hemisphere for handling spatial information. In the other task the orientation of a standard line, held in memory, was compared with the orientation of a single test line projected to the left or right of fixation. Results were in the same direction as before, although the right hemisphere superiority was significant only for the "different" responses. Data do not support the idea that "same" and "different" judgments need be differentially lateralized. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retrieval selectivity in memory-based impression judgments.

Judgments about others are often based on memory for information about the persons being judged. Three studies with a total of 92 undergraduates are reported that used decision time to determine what information Ss selectively recall when they make memory-based person judgments. Each study employed a sequential judgment paradigm in which an S first made an impression judgment about a person on one dimension while stimulus information was continuously available. Immediately therafter, the S made a 2nd judgment about the same person on a different dimension without the stimulus information being available. It is concluded that Ss' memory-based judgments were based on memory for their 1st impression judgments combined with a selective memory search for negative stimulus information. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)