Lateralization of phonology 2 DAY 23 – Oct 21, 2013

1. Lateralization of phonology2DAY 23 – Oct 21, 2013 Brain & Language LING 4110-4890-5110-7960 NSCI 4110-4891-6110 Harry Howard Tulane University

2. Brain & Language - Harry Howard - Tulane University Course organization • The syllabus, these slides and my recordings are available at http://www.tulane.edu/~howard/LING4110/. • 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.

3. Brain & Language - Harry Howard - Tulane University Review The quiz was the review.

4. Brain & Language - Harry Howard - Tulane University Lateralization of phonology 2

5. Brain & Language - Harry Howard - Tulane University 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: • the differences in form of the acoustic transitions that make up a given phonological segment • the duration of acoustic transitions • temporal vs. spectral information • categorical vs. graded relations • 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.

6. Brain & Language - Harry Howard - Tulane University 1. Quality of transitionsnote the difference in appearance between [b] & [p]

7. Brain & Language - Harry Howard - Tulane University 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.

8. Brain & Language, Harry Howard, Tulane University Dichotic listening

9. Brain & Language - Harry Howard - Tulane University 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.

10. Brain & Language - Harry Howard - Tulane University What is a spectrum?

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

12. Brain & Language - Harry Howard - Tulane University 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.

13. Brain & Language - Harry Howard - Tulane University 4. 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 coordinatedistinctions. • 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.

14. Brain & Language - Harry Howard - Tulane University 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?

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

16. Brain & Language - Harry Howard - Tulane University 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

17. Brain & Language - Harry Howard - Tulane University NEXT TIME Theories of lateralization