1
1
1,2
1
2
• Emotion interacts with cognition at many levels of processing, from basic perceptual 1 and attentional 2 stages to higher cognitive functions such as decision-making 3 and categorization.
4
• Findings from studies of auditory emotion recognition are mixed and include reports of enhanced processing of negative 5 , positive, 6 and neutral 7 prosody.
• Is there enhanced processing of negative prosody?
• Or, is there an advantage for emotional (positive or negative) compared to non-emotional prosody?
• Two experiments , Behavioral (Exp. 1a & 1b) and
Electrophysiological (Exp. 2), aim to explore these questions.
• 43 UCSD undergraduates (monolingual native English speakers, 27 female, mean age = 21)
•Stimuli: 48 Jabberwocky sentences (mean length = 2.7s), recorded by a
Native English female speaker at a regular rate of speech (approx 5 syll/sec), were spoken in happy, angry, and neutral prosody
• Gating paradigm: 8 Sentences edited into successive clips, with duration increasing in 250ms increments; 5s of silence in between (Figure 1 below)
“The hessups ate pea chup after the sholt.”
250ms
500ms
750ms ...
Entire Sentence
Figure 1. Schematic of a spliced sentence
• Mixed factorial design: all participants received all emotions, but no one participant heard any sentence more than once
• Participants randomly assigned to 1 of 3 groups:
Group 1
Sentences 1-16 Sentences 17-32 Sentences 33-48
HAPPY ANGRY
Group 2
Group 3
ANGRY
NEUTRAL
NEUTRAL
HAPPY
• Every clip judged to be happy, angry, or neutral
NEUTRAL
HAPPY
ANGRY
• Variables of interest:
• Percent correct
• Isolation point (length of the clip at which participants chose the correct emotion and did not subsequently change their decision)
• 24 UCSD undergrads (monolingual native English speakers, mean age = 22)
• Stimuli: same as in Experiment 1a
• Similar design as above: participants randomly assigned to 1 of 4 groups:
Group 1
Group 2
Group 3
Group 4
Sentences 1-24
ANGRY
NEUTRAL
HAPPY
NEUTRAL
Sentences 25-48
NEUTRAL
ANGRY
NEUTRAL
HAPPY
• Greater accuracy for neutral prosody,
F (2,
34) = 7.87, p = .001:
*
100
**
90
80
70
60
50
Happy Angry
Emotion
Figure 2
Neutral
= .001
Neut ral > Angry, p
= .001;
< .05
• Faster correct identification of neutral prosody, F (2, 34) = 24.67, p = .000:
1000 *
***
802.28
**
722.88
750
500 443.71
250
Happy Angry
Emotion
Figure 3
Neutral
* Neutral < Happy,
** Neutral < Angry, p
p
< .001
= .001
*** Angry < Happy, p < .05
• Greater accuracy for neutral prosody than happy prosody, t (11) = 3.52, p = .003, or angry prosody, t (10) = 4.48, p = .001.
• Faster correct identification of neutral prosody than happy t (11) = 2.23, p = .024, or angry prosody, t (10) = 3.06, p = .006.
• Participants in Experiments 1a and 1b demonstrated a processing advantage for neutral prosody, which was identified more accurately and more rapidly than happy or angry prosody.
• This ‘neutral bias’ was not simply due to a greater ease in discriminating emotional from non-emotional prosody.
• Does the “neutral bias” observed in
Experiments 1a and 1b reflect perception, attention, decision/response, or a language processing or acoustic parameter?
• 13 UCSD undergrads (right-handed monolingual native English speakers, mean age = 21; note that this experiment is part of a larger study that is still in progress.)
• Stimuli: Jabberwocky sentences from Experiment 1 (presented in their entirety; i.e., not spliced), alternating with tone sequences of ascending, descending, and constant pitch
• Target detection task:
• 6 blocks of trials; each emotion (happy, angry, neutral) served as a target in 3 blocks; order counterbalanced
• Participants instructed to press one button (right/left counterbalanced across subjects) following a Jabberwocky sentence conveying the target emotion, and the other button following any other type of audio clip
• EEG recording and ERP reduction:
• Quik-Cap (CompuMedics,
Inc.) with 32 sintered Ag/AgCl electrodes arranged according to modified international 10-20 system placement (Figure 5)
Figure 4
• EEG amplified 100x with a SynAmps amplifier; electrodes referenced to linked mastoids
• Incorrect trials excluded, as well as time windows containing artifacts
• Participants whose data yielded >70% trial inclusion were retained for data analysis (n = 11).
• ERPs to Jabberwocky emotional prosody stimuli time-locked to the average isolation point for each emotion, as determined in Experiment
1a, in order to examine the recognition process (reference Fig. 3)
• Data analysis: Repeated measures ANOVAs; Greenhouse-Geisser adjustment applied to correct for sphericity violations
• Time windows of interest: -400 – 0ms, 600 – 2000ms
• -400 – 0 window: significant effect of emotion maximal at Pz, P3/4, Oz, and O1/2
• Amplitudes in neutral condition significantly more negative than in happy or angry conditions
(all p s ≤ .001), which did not differ from one another:
Figure 5
Figure 5
• 600 – 2000 window: significant effect of emotion maximal at FT7/8
• Sustained positivity in neutral condition significantly greater than in happy or angry conditions
(all p s ≤ .001), which did not differ from one another:
Figure 6
• ERP data indicate a negative deflection in the 400ms preceding the isolation point, which likely reflects emotion recognition processes.
• Neutral prosody elicited a greater amplitude positivity between 600-
2000ms than emotional prosody.
• Behavioral and ERP data support a bias for processing neutral prosody over happy and angry prosody.
• Future directions include comparing task-relevant vs. task-irrelevant processing of emotional prosody.
1 Phelps et al (2006). Psych. Science , 17, 292-299.
2 Carretié et al (2003).
Psychophys., 40, 381-288.
3 Bechara, Damasio, & Damasio (2003). Ann. NY Academy
Sciences, 985 , 356-369.
4 Ito et al. (1998). J Personality and Social Psych., 75, 887-
900.
5 Wambacq, Shea-Miller, & Abubakr (2004). NeuroReport,
15 , 555-559
6 Alter et al (2003). Speech Communication, 40 , 61-70.
7 Schirmer & Kotz (2003). JCN, 15 , 1135-1148.
8 Grosjean, F. (1980). Perception & Psychophys., 28, 267-
283.
• This research was supported in part by an NSF Graduate
Research Fellowship to the first author and NIH grants
(DC00494 and DC03885) to the last author.
• Special thanks to Sarah Callahan, Hong Duong, Maxwell
Moholy, Negin Khalifian, Hoa Nguyen, Uyen Pham, Sara
Rust, Danny Sanchez, and Matt Walenski!