LATERALIZATION OF PHONOLOGY 2 DAY 23 – OCT 21, 2013 Brain & Language LING NSCI Harry Howard Tulane University

Course organization The syllabus, these slides and my recordings are available at If you want to learn more about EEG and neurolinguistics, you are welcome to participate in my lab. This is also a good way to get started on an honor's thesis. The grades are posted to Blackboard. 10/21/13Brain & Language - Harry Howard - Tulane University 2

REVIEW The quiz was the review. 10/21/13Brain & Language - Harry Howard - Tulane University 3

LATERALIZATION OF PHONOLOGY 2 10/21/13Brain & Language - Harry Howard - Tulane University 4

10/21/13Brain & Language - Harry Howard - Tulane University 5 Lateralization of acoustic cues or parameters Cue or parameter models seek hemispheric specialization in some component of the acoustic signal which either flags a semantic construct (a cue) or constitutes a broad physical measure (a parameter). I know of five well-articulated positions that have been set forth as the defining cue or parameter of hemispheric specialization: 1. the differences in form of the acoustic transitions that make up a given phonological segment 2. the duration of acoustic transitions 3. temporal vs. spectral information 4. categorical vs. graded relations 5. the frequency of information in general Normal speech confounds these hopelessly, so it will be quite a challenge to tease out and evaluate the contribution of any single.

10/21/13Brain & Language - Harry Howard - Tulane University 6 1. Quality of transitions note the difference in appearance between [b] & [p]

10/21/13Brain & Language - Harry Howard - Tulane University 7 2. Duration of transitions Early research pointed to the importance of duration over transition. For instance, Kimura’s initial experiments with dichotic listening uncovered the fact that right-ear superiority is most evident with stimuli containing rapid changes in the acoustic spectrum … not only in normal speech, but also in nonsense syllables and in speech played backwards. Furthermore, while the right-ear advantage is most marked with relatively brief stop consonants, the effect is minimal or disappears with vowels. Vowels are linguistic entities, but the time course over which the critical information is present is considerably longer than with consonants. Recall the next slide.

Dichotic listening Tendencies of right-ear advantage by speech sound No advantageWeak right-ear advantageStrong right-ear advantage vowels liquids (l,r), glides (j,w), fricatives stops the acoustic cues for vowels do not depend on context the acoustic cues for consonants depend on context [see p. 116] > special machinery? longmediumshort 9/30/11Brain & Language, Harry Howard, Tulane University 8

10/21/13Brain & Language - Harry Howard - Tulane University 9 3. Temporal vs. spectral features Some researchers have taken this work in a slightly different direction by postulating a qualitative differentiation in the cues that the two hemispheres are sensitive to: the LH has a higher resolution for temporal information, the RH has a higher resolution for spectral information.

What is a spectrum? 10/21/13Brain & Language - Harry Howard - Tulane University 10

Where is a spectrum in speech? 10/21/13Brain & Language - Harry Howard - Tulane University 11 So what is resolution, or temporal vs spectral resolution?

10/21/13Brain & Language - Harry Howard - Tulane University 12 A musical experiment Zatorre & Belin (2001) used PET to examine the response of human auditory cortex to spectral and temporal variation. Volunteers listened to sequences derived from a stimulus consisting of two pure tones separated by one octave alternating with a noise. In one condition, spectral information remained constant while speed of alternation was doubled at each level. So the same pitch was heard at an increasing rate. In the other, speed was kept constant while the number of tones sampled within the octave was doubled at each level. So the time period contained an increasing number of pitches. Results indicated that … responses to the temporal features were weighted towards LH, while responses to the spectral features were weighted towards RH.

10/21/13Brain & Language - Harry Howard - Tulane University Categorical ~ graded or coordinate distinctions Others argue that it cannot be a simple specialization of the LH for temporal processing and the RH for spectral processing, especially fundamental frequency, because RHD patients are deficient in both. What is more plausible is that … the LH encodes categorical distinctions, while the RH encodes graded or coordinate distinctions. By categorical, we mean those distinctions that are all or none, such as whether a word bears focal stress or not, or whether a dot is above or below a bar (see next slide). By graded or coordinate, we mean those distinctions that can take on many values, such as whether a dot is near or far from a bar (see next slide). Emotion is a natural choice for expression via a graded phenomenon, since one’s emotional arousal is itself a graded state.

Categorical vs. graded or coordinate spatial relations Is the black dot above or below the bar? Is the black dot near or far from the bar? 10/21/13Brain & Language - Harry Howard - Tulane University 14

Categorical vs. graded or coordinate phonological features all or nothing the lexical stress of CONvert the high tone of baa the compound stress of HOTdog stops? gradations emotional intonation intonation of sentence type? vowels? 10/21/13Brain & Language - Harry Howard - Tulane University 15

A conversion to resolution Left hemisphere, fine coding: 9 neurons index 9 regions of space Right hemisphere, coarse coding: 4 neurons index 12+ regions of space 10/21/13Brain & Language - Harry Howard - Tulane University 16

NEXT TIME Theories of lateralization 10/21/13Brain & Language - Harry Howard - Tulane University 17