Perceptual overestimation of rising intensity: is stimulus continuity necessary?
A "perceptual bias for rising intensity" (Neuhoff 1998, Nature 395 123-124) is not dependent on the continuous change of a dynamic, looming sound source. Thirty participants were presented with pairs of 500 ms steady-state sounds corresponding to onset and offset levels of previously used dynamic increasing- and decreasing-intensity stimuli. Independent variables, intensity-change direction (increasing, decreasing), intensity region (high: 70-90 dB SPL, low: 50-70 dB SPL), interstimulus interval (ISI) (0 s, 1.8 s, 3.6 s), and timbre (vowel, violin) were manipulated as a fully within-subjects design. The dependent variable was perceived loudness change between each stimulus item in a pair. It was hypothesised that (i) noncontinuous increases of intensity are overestimated in loudness change, relative to decreases, in both low-intensity and high-intensity regions; and (ii) perceptual overestimation does not occur when end-levels are balanced. The hypotheses were partially supported. At the high-intensity region, increasing stimuli were perceived to change more in loudness than decreasing-intensity stimuli. At the low-intensity region and under balanced end-level conditions, decreasing-intensity stimuli were perceived to change more in loudness than increasing-intensity stimuli. A significant direction x region interaction varied as a function of ISI. Methodological, sensory, and cognitive explanations for overestimation in certain circumstances are discussed.
Olsen
Kirk N
KN
MARCS Auditory Laboratories, University of Western Sydney, South Penrith DC, NSW 1797, Australia. k.olsen@uws.edu.au
Stevens
Catherine J
CJ
D000161:Acoustic Stimulation / Q000379:methods*; D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008144:Loudness Perception / Q000502:physiology*; D008297:Male; D009039:Motion Perception / Q000502:physiology; D013997:Time Factors; D055815:Young Adult