Ensemble Perception

Imagine a speaker scanning her audience, trying to get a sense of how many of them are feeling bored. Certainly, people can estimate ensemble properties from a group of objects (e.g., average emotion from a crowd of faces, color diversity from a fruit basket). While these judgments seem trivial, they require a remarkable ability to summarize visual information within a brief moment of time. At MVL, we study whether and how ensemble judgments differ from judgments about individual objects. Our research includes, but is not limited to, the following topics:

Masked-face perception and masked-crowd perception. During the COVID-19 pandemic, people became adept at recognizing others' faces with a mask covering about half of the faces. Our research seeks to determine whether this experience has led people to i) develop new strategies to deal with visual information loss caused by face coverings, or ii) learn a new category of objects (just as a dog expert would learn to recognize wolves). We also aim to investigate whether this recognition ability extends to ensemble judgments for a crowd of masked faces.

Perception of identities and facial expressions in a crowd. Studies have shown that people's ability to identify an individual and to perceive other's facial expressions are correlated to some extent (e.g., Connolly et al. 2019). We are interested in whether this correlation persists when people are required to make ensemble judgments about both identities and facial expressions from a group of faces.

Cost-free ensemble processing. Bronfman et al. (2014) found that people could estimate the color diversity of unattended letters within a 6-by-4 grid while attending to a cued row probed later. They interpreted this finding as evidence of ensemble processing without any additional attentional cost. We propose an alternative explanation that the attentional window around the cued row may encompass several letters in the adjacent rows, which could potentially contribute to the color diversity judgments.

Multitasking and ensemble processing. In our daily lives, we often find ourselves multitasking (e.g., glancing at our smartphone notifications during a lecture) and we can usually manage this secondary task with only a small portion of our attentional resources. Similarly, in ensemble processing experiments, people are able to perceive ensemble properties from a group of objects with only a fraction of their attention to individual objects. Our research aims to determine whether these two types of processing rely on shared mechanisms.

Rhythms of Visual Awareness

“Perceptual experience seems to unfold seamlessly, but this belies the evidence that perception comprises discrete epochs in which perceptual responsiveness varies periodically over time” (Cha & Blake, 2019). In other words, our ability to respond to changes in the visual environment waxes and wanes over time. Recent studies suggest that these fluctuations may reflect neural oscillations associated with shifting/employing attention to a new location or stimulus. At MVL, we will explore whether visual awareness fluctuates in accordance with fluctuation in perceptual responsiveness.

We utilize binocular rivalry to study changes in visual awareness without any corresponding changes in the visual environment. To experience these changes for yourself, try viewing the images below with red-blue anaglyph glasses on, and then attempt to view the images with each eye closed.