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Feature integration and auditory scene analysis
At the recent ASA meeting in Ottawa, Richard Pastore brought up
Treisman's feature integration theory in a discussion of higher level
auditory processing (2pMU3). As I (naively and grossly) understand its
application to vision, this theory assumes that, in an analysis of
incoming stimuli, several different, rapid processes (such as the
determination of the color in each area of the visual field) are
performed in parallel, and that at a higher level the output of these
different processes (features) are integrated together to form the
percepts of objects. This dichotomy is revealed in tasks such as
determining whether a green figure is present in a background of
non-green figures (rapid response time for criterion performance), and
finding a particular green figure (say, a green X) amongst other
multi-colored figures (for criterion performance, this occurs more
slowly). The former is associated with the rapid processes (such as
identifying the existence of a color), and the latter is associated
with the slower, presumably "higher-level" process of forming
conjunctions between features (such as color and shape). Thus, the
name "feature integration". I believe several glimpses of
feature-integration-like effects were apparent in talks at the Ottawa
conference, in addition to those discussed by Dr. Pastore.
In a talk by Bill Yost (3aMU1), it was noted that detecting the
presence of modulation at one carrier was made difficult when other
potential carriers existed in the stimulus. This is similar, as Dr.
Yost pointed out, to results reported by Hall and Grose [JASA 90(6)]
in which listeners (3 out of 4, at least) could identify the PRESENCE
of modulation at modulation depth thresholds lower than those for
which they could identify the carrier frequency of the modulation.
Later in the same session (3aMU3), Bill Hartmann discussed
difficulties with detecting a given mistuned harmonic of a complex
when a second mistuned harmonic was present. These difficulties
(associating modulation with a carrier, associating mistuning with a
particular reference frequency) have the flavor of the feature
integration tasks. That is, detecting whether modulation (or
mistuning, in the latter example) exists is analogous to detecting the
presence of a particular color (relatively low threshold), and
detecting whether a particular carrier frequency is modulated (or
mistuned) is analogous to detecting whether a form with a certain
color is present (relatively high threshold). In one case, a
particular feature must be detected. In the other case, one feature
(carrier freq) must be associated or connected to another feature
(modulation or mistuning).
I do not mean to imply that Treisman's integration theory
"explains" these results. Rather, to re-iterate, perhaps, some of Dr.
Pastore's intent, I mean only to imply that the analogy between
current work on auditory scene analysis and past work on visual scene
analysis may well go beyond the Gestalt principles, that several
examples of further analogy already exist, and that understanding the
successes and failures encountered by theories such as Treisman's,
before a great deal of these (successes, failures, and theories) are
re-discovered or re-invented by we auditory scene analysis
researchers, may lead to substantial gains for comparatively less
effort (and that I can write a whopper of a run-on sentence).
I hope this has been informative.