Detection and recognition of intensity changes in tone and noise: The detection-recognition disparity

118

Past studies of simultaneous attention to pairs of visual stimuli have used the "dual-task" paradigm to show that identification of the direction of a change in luminance, whether incremental or decremental, is "capacity-limited," while simple detection of these changes is governed by "capacity-free" processes. On the basis of that finding, it has been suggested that the contrast between identification and detection reflects different processes in the sensory periphery, namely the responses of magno-and parvocellular receptors. The present study questions that assertion and investigates the contribution of central processing in resource limitation by applying the dual task to a situation in which one stimulus is auditory and one is visual. The results are much the same as before, with identification demonstrating the tradeoff in performance generally attributed to a limited capacity but detection showing no loss compared with single-task controls. This implies that limitations on resources operate at a centrallevel of processing rather than in the auditory and visual peripheries.In divided attention, performance limitations depend on a variety of features of both the stimulus and the response (see Duncan, 1980, andHirst, 1986, for review). Recently, Bonnel, Stein, and Bertucci (1992) showed that limitations may also depend on the nature of the psychophysical paradigm. They used the dual-task methodology to present concurrent visual stimuli in two paradigms, "detection" and "identification." Subjects responded separately to simultaneous side-by-side visual channels. In detection, signals were increments in luminance S(+) that could be added to each channel independently. In identification, signals were either increments S(+) or decrements S( -) that were added to each stimulus independently. Thus, in detection, subjects monitored for the presence of signals whereas in identification they identified the signs ofsignals. Results indicated no effect ofconcurrence when the task was to detect, but clear deficits when the task was to identify.Greater understanding of divided attention in the dual task is revealed by "attention-operating characteristics" (AOCs), which plot joint performance as a function of attentional instructions (e.g.,

Section: ---~-~-~----------------------Dmentioning

confidence: 99%

Divided attention between simultaneous auditory and visual signals

Bonnel

Haftser

1998

118

“…MacMillan (1971MacMillan ( , 1973 used signals like those of Garner and Miller and confirmed their results concerning the effect of increment duration. Neither of these investigators, however, demonstrated that there are no effects of increment duration beyond 500 msec.…”

mentioning

confidence: 67%

“…MacMillan (1971MacMillan ( , 1973 has argued in favor of the last of these three alternatives, basing his argument on data concerning both recognition and detection.…”

Section: Theoretical Notesmentioning

confidence: 99%

“…The change detector operates on changes in signal level, such as our steps, and the integrative detector "accumulates information about the stimulus over time" (MacMillan, 1973). The outputs of the two detectors "combine in an unspecified manner to yield detection performance," and the output of the integrative detector is sensitive to signal duration, while that of the change detector is not.…”

Section: Theoretical Notesmentioning

confidence: 99%

See 1 more Smart Citation

On the detection of stepwise changes in a constant signal level

Kristofferson

Allan

Campbell

1981

A stepwise change in the frequency of a continuous pure tone is taken as an element signal. The detectability of a single step is compared with the detectability of a pattern composed of two such steps in order to determine the ways in which the steps interact and how these interactions depend upon the time interval between the steps. It is shown that two positive steps separated by D msec interact by summation (d' for two steps being greater than d' for a single step) and that this summation is 100% even when D=100 msec. The extent of summation decreasesas D is increased beyond100msec, levelingoffat about 40% when D is near 1,000msec. A positive step followed by a negative step (an increment) presents a more complex picture. When D=O msec, the pattern is the null signal, and, of course, the two steps subtract completely. As D is increased, the extent of subtraction decreases, becomingzero when D is about 400 msec. Increasing D beyond 400 msecresults in summation, reaching about 40% when D=2,000 msec. For D less than about 1,000 msec, the sign of the second step in a two-step signal is important: two steps of like sign summate, and two steps of unlike sign subtract. However, when the two steps are separated by about 2,000 msec, the sign of the second step is irrelevant: summation occurs,and the extent, about 40%,is the same for two steps of like sign and two steps of unlike sign. A brief theoretical discussion stresses the extant need for an information-processing theory of signal detection.

“…Under these conditions, the probability of response appears to be determined by the duration of the silent period between stimuli rather than by repetition rate per se. The recent work of Hafter and his associates (Dye & Hafter, 1984;Hafter, Dye, & Wenzel, 1983) demonstrates another parallel between the response properties of these "on" type units and interaural dis- The existence of two parallel systems specialized for processing transient and sustained aspects of stimulation has been well established for the visual system (Breitmeyer & Ganz, 1976), and a similar organization of the auditory system has been inferred from differences between detection and recognition performance in perceptual tasks (Macmillan, 1971(Macmillan, , 1973, from analysis of reaction time data (Burbeck & Luce, 1982) and from the response characteristics of auditory neurons (Gersuni, 1971). The results of the present series of experiments also appear to be consistent with this type of organization if, in addition, one assumes that information from short-and longterm integration systems is combined at higher centers when analysis of interaural differences within each of the systems yields similar estimates of lateral position or spa- o c « crimination in human subjects.…”

Section: Resultsmentioning

confidence: 99%

Temporal masking level differences for transients: Further evidence for a short-term integrator

Berg

1985

Studies of binaural perception have indicated that subjects are able to use temporal information available in high-frequency regions of the spectrum to lateralize high-frequency waveforms but not to detect these waveforms in masking noise. The present experiments demonstrate that although high-frequency interaural difference cues are relatively ineffective in simultaneous and forward masking, they can be utilized in backward masking. In Experiment 1, large maskinglevel differences were found in backward masking for high-frequency transients presented either monaurally or with an interaural temporal delay. Experiments 2-4 examined fringe masking, effects of masker duration, and combined forward-backward masking for both high-and lowfrequency transients presented with interaural differences in phase and intensity. The results are interpreted as support for the view that the auditory system is organized into parallel shortand long-term integration systems specialized for processing transient and sustained aspects of acoustic stimulation. It is suggested that information from the two integrators is combined when analysis of interaural differences within each of the systems yields similar estimates of spatial location.One of the many advantages of perceiving the world through two ears rather than one is the enhanced ability to distinguish signals from a background of interfering noise. When the interaural phase or temporal parameters of an auditory signal differ from those of a background masking noise, the signal may be detected at a much lower level than when interaural parameters of both the signal and noise are the same. This binaurally mediated increase in detectability is frequently referred to as the "cocktailparty" effect, and has been systematically investigated in the laboratory as the binaural masking-level difference, or MLD. Factors affecting the size of the MLD are also those that affect sound localization or lateralization, and the two phenomena are generally considered to be closely related.A number of models have been developed to explain the various phenomena of binaural perception. Those most successful in accounting for the MLD have been the Webster-Jeffress model (Jeffress, 1972), which proposes that the MLD is based on detection of interaural time differences arising from the combination of the signal and noise waveforms present at each ear, and Durlach's (1972) equalization-eancellation model, in which a signal is extracted from noise by subtraction of the two monaural waveforms. Many aspects of these models have been elaborated and quantified in the more recent work of Colburn (1977; based on firing patterns of the auditory nerve.