1. Paul J. Reber Department of Psychology Northwestern University
Reflections…
Paul J. Reber
Department of Psychology
Northwestern University

2. Paul J. Reber Department of Psychology Northwestern University
How the hell did I end up spending the last 15 years studying “Category Learning”?
Paul J. Reber
Department of Psychology
Northwestern University

3. “Category Learning”
“You do research at Northwestern? What do you study?”
Dogs versus Cats, Trees versus Bushes
Blah blah blah
A PR problem…

4. What is Category Learning?
Ask the Great Gazoogle
Link 1: Annual Review of Psych (2005), Ashby & Maddox
Link 2: Wikipedia
Category:Learning
From Wikipedia, the free encyclopedia
The main article for this category is Learning.
Subcategories
There are 5 subcategories in this category, which are shown below. More may be shown on subsequent pages.

5. What is Category Learning?
Dot patterns
Unpronounceable strings of letters
Sine wave gratings

6. Dot patterns Learned incidentally
Associated with changes in early visual cortex
Reber, Stark & Squire, 1998a
Reber, Stark & Squire, 1998b
Wait. Did you say early visual cortex? There’s plasticity there in the adult brain? For dot patterns? After 40 presentations? Really?
Reber at al, 2003

7. “Learning to see”
Crist & Gilbert (2001). Learning to see: experience and attention in primary visual cortex. Nature Neuroscience.
Non-classical receptive field effects in early visual cortex
Single-cell electrophysiology
Task dependent firing changes
Schäfer, Vasilaki, & Senn (2007). Perceptual learning via modification of cortical top-down signals. PLoS Computational Biology.
How to do perceptual learning in V1 without screwing up perception

8. Unpronounceable Letter StringsH P J T
“Reber” grammar
Artificial Grammar Learning
Intact in amnesic patients
AD patients
Posterior parietal cortex
Association cortex
Symbol manipulation P J X H V X V T
+32
G > NG
Who called this paradigm “grammar” learning anyway? XTXPHV? That’s not even a word, much less grammatical. Language has deep structure, reference, meaning…

9. Learning language
Saffran (2003). Statistical language learning: mechanisms and constraints. Current Directions in Psych Science.
“…Recent evidence suggests that learners, including infants, can use statistical properties of linguistic input to discover structure, including sound patterns, words, and the beginnings of grammar. These abilities appear to be both powerful and constrained…”
How much language learning can be done without the frontal lobes?
Meaning, reference, deep structure

10. Implicit learning vs Rule-based
Sine wave gratings
Category learning with feedback
Depends on cortico-striatal loops between the posterior caudate and visual cortex
When not accomplished by PFC-MTL
If dot patterns = learning to see and AGL = learning language, learning to call stripy things an ‘A’ is… um, learning to drive? learning to play tennis? learning to be a doctor?
Implicit learning vs Rule-based
(composite)

11. Diagnosing sleep stage from EEG
Expert diagnosticians read continuous collected EEG traces from sleeping individuals and identify occurrence and duration of sleep stages
Novices were briefly trained to discriminate REM and Slow Wave sleep from EEG snippets
fMRI data collected after 1 day and 1 week of training
Opposing movements in the eye channels mark REM sleep

12. Neural correlates of diagnosis
After 1 week of training, increased activity emerged in a cortico-striatal loop
Selective for trained stimuli
Left Fusiform
Right Caudate

13. “Category Learning” Is everything, after all
Learning to see, learning language, expertise
Plasticity, memory, categories are everywhere in the brain