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Re: Increment versus decrement detection
Bruno Repp wrote:
I recently conducted some experiments in which participants had to
detect a single changed tone in an isochronous melody consisting of 12
successive complex tones (piano tones) of different pitch but equal
loudness. The change to be detected was either in intensity or in
duration, and it was either an increment or a decrement. These were
four separate tasks, not intermixed. The melody containing the change
was immediately preceded by the same melody not containing any change.
I would be grateful for comments or references that would help me
understand the following trends in my data:
(1) Decrements are harder to detect than increments. Is this well
known from previous psychoacoustic research? What is the reason?
You are perhaps familiar with David Huron, "The Ramp Archetype and the
Maintenance of Passive Auditory Attention",
Music Perception, Vol. 10, No. 1 (1992) pp. 83-92. According to the
abstract, "increases of stimulus intensity level are
more effective than equivalent decreases in evoking listeners'
attention." Huron uses this to explain the fact that
it's more usual in music to build slowly & decrease quickly rather than
the opposite. I haven't read the paper, but
I assume his argument is grounded in evolutionary psychology ideas about
the relative advantages of precise detection of increase
in things rather than decrease. As one approaches things (or is
approached by things) they become larger: something becoming smaller,
ie running away, doesn't seem to benefit from a precise perceptual
calibration of size difference.
(2) The pattern of variation in detection scores (hits and false
alarms) across the 12 tones in the melody, which reflects influences
of pitch contour and other factors, is uncorrelated between increment
and decrement detection. It seems like these two tasks have little in
I'm not sure I understand what you mean by "influences of pitch contour"
here. Is there some reason why this experiment requires a
melody as opposed to repeating just one note, or making simple
variations on two notes, like CCDDCCDD, etc? Also, why did you choose
(3) In increment detection, both hits and false alarms tend to
increase across the 12 tones in a melody, but decrement detection
shows the opposite trend. It is as if tones were expected to become
softer as the melody progresses. Why?
There may be a problem with listener fatigue, something equivalent to
the habituation of the orienting reflex. Interest
is at its highest at the start, declining as the tune rolls on, if the
tune happens to be a not very good one. Assuming that
we're more interested in increments than decrements, listeners are
overcompensating for even movement at the start, where they
more attentive than later. The more interesting thing is increase,
because it's more indicative of interesting movement,
as per above. So that's what listeners are priming themselves for, and
why they would misjudge earlier, or something like that.
I agree with Kevin that it's not possible to say much without knowing
what the melodies were.
Many thanks in advance for any helpful replies!