When aging or neurological disease affects memory, people often say it feels as if their loved one “is no longer there.” This irreplaceable role of memory in shaping one’s identity and behavior makes it particularly important to clarify how the content of our memory – such as its quantity, quality, and subjective value – is represented and processed to support diverse mental functions. Furthermore, memory also offers a unique window into the functions of the brain. By understanding how memory is formed and retrieved, we may begin to uncover the brain’s underlying organizational principles – insights that may one day help us better understand complex human experiences like affect, decision-making, and mental health.
To explore these questions, our lab takes a multidisciplinary approach to studying human memory across different timescales, contexts, and individuals. We use tools ranging from mathematical modeling and crowdsourcing to fMRI, (i)EEG, MEG, eye-tracking, brain stimulation, and lesion case studies. Most recently, we’ve been fortunate to work with rare datasets that allow us to record directly from individual cortical neurons in awake, behaving humans – a uniquely detailed view of human memory in action.
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Despite large individual differences in memory performance, people remember certain things with overwhelming consistency. This paradoxical phenomenon, in part, is driven by our prior associative knowledge. People are more likely and fluent to recall things that share a wide connection with other stuff, just like how a Web search engine would pull out information from the internet. An important area of research in the lab is to understand what drives the consistency in memory likelihood across people, and how they change as a function of age and clinical conditions.
Representative work: Xie, W., Bainbridge, W. A., Inati, S., Baker, C. I., & Zaghloul, K. A. (2020). Memorability of words in arbitrary verbal associations modulates memory retrieval in the anterior temporal lobe. Nature Human Behaviour, 4(9), 937-948. PDF.
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While some of our memories are vivid and precise, others are foggy and fuzzy. Why do our memories vary in the degree of quality? Our work shows that the medial temporal lobe is essential for memory quality even at the scale of a few seconds. These findings offer a parsimonious explanation for altered short- and long-term memory quality under emotional contexts and in aging/clinical populations.
Representative work: Xie, W., Chapeton, J.I., Bhasin, S., Zawora, C., Wittig, J.H., Inati, S.K., Zhang, W., Zaghloul, K.A. (2023). The medial temporal lobe supports the quality of visual short-term memory representation. Nature Human Behaviour. Advanced online version. PDF.
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Trying to remember something is not always easy. When given a choice, people often would rather perform a more strenuous physical task — or even receive an electrical shock — in exchange for skipping a memory task. How does the human brain compare the value of remembering relative to other non-memory alternatives? Is remembering intrinsically effortful? Will memory-related effort increase as we age? Our recent research has tried to tackle these questions in both younger and older adults.
Representative work: Xie, W., & Zhang, W. (2023). Effortfulness of Visual Working Memory: Gauged by Physical Exertion. Journal of Experimental Psychology: General. Advanced online version. PDF.