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Auditory event-related potentials associated with perceptual reversals of bistable pitch motion.

Davidson GD, Pitts MA - Front Hum Neurosci (2014)

Bottom Line: Previous event-related potential (ERP) experiments have consistently identified two components associated with perceptual transitions of bistable visual stimuli, the "reversal negativity" (RN) and the "late positive complex" (LPC).Pairs of complex tones with ambiguous pitch relationships were presented sequentially while subjects reported whether they perceived the tone pairs as ascending or descending in pitch.These two components may be auditory analogs of the visual RN and LPC, suggesting functionally equivalent but anatomically distinct processes in auditory vs. visual bistable perception.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Reed College Portland, OR, USA.

ABSTRACT
Previous event-related potential (ERP) experiments have consistently identified two components associated with perceptual transitions of bistable visual stimuli, the "reversal negativity" (RN) and the "late positive complex" (LPC). The RN (~200 ms post-stimulus, bilateral occipital-parietal distribution) is thought to reflect transitions between neural representations that form the moment-to-moment contents of conscious perception, while the LPC (~400 ms, central-parietal) is considered an index of post-perceptual processing related to accessing and reporting one's percept. To explore the generality of these components across sensory modalities, the present experiment utilized a novel bistable auditory stimulus. Pairs of complex tones with ambiguous pitch relationships were presented sequentially while subjects reported whether they perceived the tone pairs as ascending or descending in pitch. ERPs elicited by the tones were compared according to whether perceived pitch motion changed direction or remained the same across successive trials. An auditory reversal negativity (aRN) component was evident at ~170 ms post-stimulus over bilateral fronto-central scalp locations. An auditory LPC component (aLPC) was evident at subsequent latencies (~350 ms, fronto-central distribution). These two components may be auditory analogs of the visual RN and LPC, suggesting functionally equivalent but anatomically distinct processes in auditory vs. visual bistable perception.

No MeSH data available.


Related in: MedlinePlus

Frequency spectrum diagram of the first (pure) tone (red) and the second (Shepard) tone (blue) of the bistable tritone stimulus employed in the current experiment. The horizontal axis is logarithmic reflecting perceptual as opposed to physical distances between frequencies. The musical staff (upper right) shows the two possible perceived pitch movements from tone 1 to tone 2. Due to the pitch ambiguity of tone 2, listeners perceive this pitch as either E4 or E5, which results in ascending or descending pitch percepts relative to tone 1.
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Figure 1: Frequency spectrum diagram of the first (pure) tone (red) and the second (Shepard) tone (blue) of the bistable tritone stimulus employed in the current experiment. The horizontal axis is logarithmic reflecting perceptual as opposed to physical distances between frequencies. The musical staff (upper right) shows the two possible perceived pitch movements from tone 1 to tone 2. Due to the pitch ambiguity of tone 2, listeners perceive this pitch as either E4 or E5, which results in ascending or descending pitch percepts relative to tone 1.

Mentions: Shepard tones (Shepard, 1964, 1982) are complex auditory stimuli possessing pitch class information but lacking pitch height information (e.g., a Shepard tone might be recognizable as pitch class C# while the specific C# octave is ambiguous). These tones are typically composed of ten octave-related pure-tone harmonics, the amplitudes of which are constrained by a Gaussian envelope as shown in Figure 1. When subjects are asked to make judgments about the direction of pitch motion between paired Shepard tones they inevitably use proximity as the key factor. Thus, a pair of Shepard tones built respectively on pitch classes C# and D will be perceived as ascending in pitch (a distance of 1 semitone) rather than descending (a distance of 11 semitones). When a pair of Shepard tones are exactly six semitones apart, an interval called a tritone, listeners can no longer rely on proximity to make judgments about pitch motion but will still confidently report perceiving either an ascending or descending pitch motion. Moreover, transposition up or down the scale (while maintaining the ambiguous six semitone relationship) leads the same listeners to reverse their pitch motion judgments and different listeners will often hear opposite movements when listening to the same tone pair (Deutsch, 1986). These effects are collectively referred to as the “tritone paradox” and have been extensively investigated by Diana Deutsch et al. (Deutsch, 1987, 1991, 1992, 1994, 1997; Deutsch et al., 1987; Ragozzine and Deutsch, 1994; Repp, 1994, 1997; Giangrande, 1998; Chalikia and Leinfelt, 2000; Chalikia et al., 2000).


Auditory event-related potentials associated with perceptual reversals of bistable pitch motion.

Davidson GD, Pitts MA - Front Hum Neurosci (2014)

Frequency spectrum diagram of the first (pure) tone (red) and the second (Shepard) tone (blue) of the bistable tritone stimulus employed in the current experiment. The horizontal axis is logarithmic reflecting perceptual as opposed to physical distances between frequencies. The musical staff (upper right) shows the two possible perceived pitch movements from tone 1 to tone 2. Due to the pitch ambiguity of tone 2, listeners perceive this pitch as either E4 or E5, which results in ascending or descending pitch percepts relative to tone 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126364&req=5

Figure 1: Frequency spectrum diagram of the first (pure) tone (red) and the second (Shepard) tone (blue) of the bistable tritone stimulus employed in the current experiment. The horizontal axis is logarithmic reflecting perceptual as opposed to physical distances between frequencies. The musical staff (upper right) shows the two possible perceived pitch movements from tone 1 to tone 2. Due to the pitch ambiguity of tone 2, listeners perceive this pitch as either E4 or E5, which results in ascending or descending pitch percepts relative to tone 1.
Mentions: Shepard tones (Shepard, 1964, 1982) are complex auditory stimuli possessing pitch class information but lacking pitch height information (e.g., a Shepard tone might be recognizable as pitch class C# while the specific C# octave is ambiguous). These tones are typically composed of ten octave-related pure-tone harmonics, the amplitudes of which are constrained by a Gaussian envelope as shown in Figure 1. When subjects are asked to make judgments about the direction of pitch motion between paired Shepard tones they inevitably use proximity as the key factor. Thus, a pair of Shepard tones built respectively on pitch classes C# and D will be perceived as ascending in pitch (a distance of 1 semitone) rather than descending (a distance of 11 semitones). When a pair of Shepard tones are exactly six semitones apart, an interval called a tritone, listeners can no longer rely on proximity to make judgments about pitch motion but will still confidently report perceiving either an ascending or descending pitch motion. Moreover, transposition up or down the scale (while maintaining the ambiguous six semitone relationship) leads the same listeners to reverse their pitch motion judgments and different listeners will often hear opposite movements when listening to the same tone pair (Deutsch, 1986). These effects are collectively referred to as the “tritone paradox” and have been extensively investigated by Diana Deutsch et al. (Deutsch, 1987, 1991, 1992, 1994, 1997; Deutsch et al., 1987; Ragozzine and Deutsch, 1994; Repp, 1994, 1997; Giangrande, 1998; Chalikia and Leinfelt, 2000; Chalikia et al., 2000).

Bottom Line: Previous event-related potential (ERP) experiments have consistently identified two components associated with perceptual transitions of bistable visual stimuli, the "reversal negativity" (RN) and the "late positive complex" (LPC).Pairs of complex tones with ambiguous pitch relationships were presented sequentially while subjects reported whether they perceived the tone pairs as ascending or descending in pitch.These two components may be auditory analogs of the visual RN and LPC, suggesting functionally equivalent but anatomically distinct processes in auditory vs. visual bistable perception.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Reed College Portland, OR, USA.

ABSTRACT
Previous event-related potential (ERP) experiments have consistently identified two components associated with perceptual transitions of bistable visual stimuli, the "reversal negativity" (RN) and the "late positive complex" (LPC). The RN (~200 ms post-stimulus, bilateral occipital-parietal distribution) is thought to reflect transitions between neural representations that form the moment-to-moment contents of conscious perception, while the LPC (~400 ms, central-parietal) is considered an index of post-perceptual processing related to accessing and reporting one's percept. To explore the generality of these components across sensory modalities, the present experiment utilized a novel bistable auditory stimulus. Pairs of complex tones with ambiguous pitch relationships were presented sequentially while subjects reported whether they perceived the tone pairs as ascending or descending in pitch. ERPs elicited by the tones were compared according to whether perceived pitch motion changed direction or remained the same across successive trials. An auditory reversal negativity (aRN) component was evident at ~170 ms post-stimulus over bilateral fronto-central scalp locations. An auditory LPC component (aLPC) was evident at subsequent latencies (~350 ms, fronto-central distribution). These two components may be auditory analogs of the visual RN and LPC, suggesting functionally equivalent but anatomically distinct processes in auditory vs. visual bistable perception.

No MeSH data available.


Related in: MedlinePlus