Elise A. Piazza
Investigating Real-Life Communication Using fNIRS
Our current understanding of the neural underpinnings of human communication is primarily limited to the processing of isolated components of language by individual subjects lying flat in an fMRI scanner.
Using functional near-infrared spectroscopy (fNIRS), I am beginning to investigate communication during live, naturalistic interactions between multiple people. In particular, I am interested in how neural coupling, or synchrony, between children and their caregivers underlies successful language development.
Measuring speaker-listener neural coupling with functional near infrared spectroscopy.
Liu, Piazza, Simony, Shewokis, Onaral, Hasson, & Ayaz. Scientific Reports, 2017.
Press: WIRED | Huffington Post | ScienceAlert | Schmidt Transformative Technology Award press release
Infant and adult brains are coupled to the dynamics of natural communication.
Piazza, Hasenfratz, Hasson, & Lew-Williams. bioRxiv, 2018.
Summary Statistics in Auditory Perception and Speech Production
I am interested in how humans use summary statistics to efficiently perceive complex sounds. In one study, we found that listeners represent the average pitch of an auditory sequence while failing to represent information about the individual tones in the sequence. Thus, our ability to process local detail seems to be supplanted by a more optimal "gist" representation.
In more recent work, we have shown that caregivers shift the summary statistics of their speech timbre (i.e., their unique vocal fingerprint) when speaking to infants, in a way that generalizes robustly across a variety of diverse languages.
Humans use summary statistics to perceive auditory sequences.
Piazza, Sweeny, Wessel, Silver, & Whitney. Psychological Science, 2013.
Press: UC Berkeley press release | Science Today interview
Mothers consistently shift their unique vocal fingerprints when communicating with infants.
Piazza, Iordan, & Lew-Williams. Current Biology, 2017.
Press: PBS | Science Friday | Washington Post | Discover Magazine | The Guardian | BBC | Princeton News
Perception of Musical Pitch and Timbre
I am also broadly interested in the perception of pitch and timbre in music and other naturalistic auditory environments. In one recent study, we report rapid, widespread perceptual adaptation to the timbre of a variety of natural sounds (speech, animal calls, musical instruments). Our results point to timbre as a high-level, configural property of sounds, processed similarly to faces in vision.
(Photo of my chamber trio in 2013).
Rapid adaptation to the timbre of natural sounds.
Piazza, Theunissen, Wessel, & Whitney. Scientific Reports, 2018.
Resolving Ambiguity in Visual Perception
How does the brain select what we consciously perceive when the world is ambiguous? My dissertation used binocular rivalry (a bistable phenomenon that occurs when two conflicting images are presented separately to the two eyes, resulting in perceptual alternation between the images) as a model of visual ambiguity to study the effects of various factors on conscious awareness.
In one study, we found that asymmetry between the two cerebral hemispheres impacts our conscious perception during rivalry. Our results indicate that conscious representations differ across the visual field and that these differences persist for a long time (>30 seconds) after the onset of a stimulus. In a follow-up study, we found that this hemispheric filtering is based on a relative comparison of available spatial frequencies in the current environment.
In another set of studies, we investigated how prediction informs perception. First, we showed that people are more likely to perceive a given image during binocular rivalry when that image matches the prediction of a recently-viewed stream of rotating gratings. More recently, we have found that arbitrary associations between sounds and images (established during a brief, passive statistical learning period) bias what we see during rivalry.
Persistent hemispheric differences in the perceptual selection of spatial frequencies.
Piazza, & Silver. Journal of Cognitive Neuroscience, 2014.
Relative spatial frequency processing drives hemispheric asymmetry in conscious awareness.
Piazza, & Silver. Frontiers in Psychology, 2017.
Predictive context influences perceptual selection during binocular rivalry.
Denison, Piazza, & Silver. Frontiers in Human Neuroscience, 2011.
Rapid cross-modal statistical learning influences visual perceptual selection.
Piazza, Denison, & Silver. Journal of Vision, 2018.