Faculty
My
research, broadly defined, is concerned with the cognitive and
neural mechanisms of learning and memory. In particular, I focus
on the ability of individuals to learn novel categories – that
is, the process by which people acquire the ability to assign
objects in the environment to different groups. I use a number
of methodological approaches in my research, including traditional
cognitive experiments with college-aged and elderly individuals,
experiments with individuals with neurodegenerative disorders
and brain injury due to stroke, and computational modeling.
My research encompasses four central issues in category learning:
1) The single versus multiple systems debate; 2) The role of
working memory; 3) The utility of conceptualizing category learning
as a motor skill; and 4) Investigating the neurobiological substrates
of category learning.
Recent Publications
Ell,
S., W. & Ashby, F. G. (2006). The effect of category
overlap on the decision strategy in information-integration
and rule-based category learning tasks. Perception
& Psychophysics, 68, 1013-1026.
Ell,
S. W., Marchant, N. L., & Ivry, R. B. (2006).
Focal putamen lesions impair learning in rule-based,
but not information-integration categorization tasks. Neuropsychologia, 44, 1737-1751.
Ashby,
F. G., Ell, S. W., Valentin, V. V., & Casale, M.
B. (2005). FROST: A distributed neurocomputational
model of working memory maintenance. Journal
of Cognitive Neuroscience, 17, 1728-1743.
Ell,
S. W., & Ashby, F. G. (2004). Dynamical trajectories
in category learning. Perception & Psychophysics,
66, 1318-1340.
Ashby,
F. G., Ell, S. W., & Waldron, E. M. (2003). Procedural
learning in perceptual categorization. Memory &
Cognition, 31, 1114-1125.
Ashby,
F. G., Noble, S., Filoteo, V., Waldron, E., & Ell,
S. W. (2003). Category learning deficits in Parkinson’s
disease. Neuropsychology, 17, 115-124.
Ashby,
F. G., & Ell, S. W. (2002). Single versus multiple
systems of category learning: Reply to Nosofsky and
Kruschke (2001). Psychonomic Bulletin & Review,
9, 175-180.
Ashby,
F. G., & Ell, S. W. (2002). Single versus multiple
systems of learning and memory. In J. Wixted (Ed.), Steven’s Handbook of Experimental Psychology: Vol.
4. Methodology (3rd ed.). New York: Wiley.
Ashby,
F. G., & Ell, S. W. (2001). The neurobiology of
human category learning. Trends in Cognitive Sciences,
5, 181-225.
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