1. Priming, Implicit Memory, and the Brain:
A Neuroimaging Perspective
Daniel L. Schacter
Harvard University

2. Acknowledgements Memory Lab, Harvard Psychology
Donna Addis
Elissa Aminoff
Elizabeth Chua
Rachel Garoff-Eaton
Angela Gutchess
Dale Stevens
Gagan Wig
Alana Wong
Athinoula A. Martinos Center for Biomedical Imaging
Supported by NIMH and NIA

3. MYSTERY

4. APRICOT

5. CUPCAKE

6. ASSASSIN

7. _ _ES_ _X

8. _UP_ _KE

9. Tulving, Schacter, & Stark (1982)

13. Picture Fragment ID after 17 Years (M Age = 39.2; Mitchell, 2006)

14. *Unaffected or even reduced by semantic or elaborative
Some Properties of Priming on Stem Completion,
Fragment Completion and Identification Tests
*Unaffected or even reduced by semantic or elaborative
encoding manipulations that enhance recall and recognition.
*Sensitive to changes between study and test in the physical
features of target items: sensory modality, word font, case.
Such changes typically have smaller effects on recall and
recognition.
*Typically preserved in amnesic patients with impairments
on recall and reocgnition tests.

15. Characterizing Dissociations: Memory Systems
Priming on tests such as completion and identification
is little affected by semantic processing and highly
dependent on physical features of stimuli.
Led to postulation of perceptual representation system
(‘PRS’): involves storage/retrieval of modality-
specific information that supports identification of
words/objects (Schacter, 1990;Tulving & Schacter, 1990).
“Pre-semantic” collection of susbsystems (visual
word form, auditory word form, structural description)
that depend on posterior cortical brain regions, not
hippocampus/MTL; should be preserved in amnesia.

16. Object Priming Paradigm+ + + + + + + + + + + +
2 SEC
BETWEEN
STIMULI
STUDY
TEST

17. Behavioral Performance at Test
900
850
800
750
700
REACTION TIME (MSEC)
650
600
550
500 + +
450
NOVEL
REPEATED

18. Priming-related activation decreases
Novel > Repeated Same
Reduced activation (indicating priming) for repeated objects in multiple regions, including:
Left anterior inferior frontal cortex (BA 47, 45)
Bilateral fusiform, extending into parahippocampal cortex (BA 37, 19)

19. Specificity of Priming-Related Reductions
Neural correlates of priming for:
Novel objects
Repeated same objects
Repeated different objects
18 subjects scanned while undertaking size judgements of visually-presented objects.
Koutstaal et al. (2001) Neuropsychologia

20. Fusiform Laterality Effect
Repeated Different > Repeated Same
Greater activation (indicating less priming for Different) in:
Bilateral fusiform (BA 37, 19).
Greater effect of exemplar change in Right than Left fusiform cortex

22. Explaining Activation Decrease in Object Priming
“Neural Tuning”
Wiggs, C. L., & Martin, A. (1998). Properties and mechanisms of perceptual priming. Current Opinion in Neurobiology.

23. Is Object Priming Response Specific?
High Prime
Novel
“Bigger than a shoebox? (yes/no)”
1.Start Phase
2.Switch Phase
“Smaller than a shoebox? (yes/no)”
Low Primed
High Primed
3.Return Phase
Low Prime
n = 16, Event Related, 4 - Cycles
Dobbins, Schnyer, Verfaellie & Schacter (2004) Nature

24. Is Object Priming Response Specific?a
1100
Start
Switch
Return
1000
900
Mean Reaction Time - milliseconds
800
700
600
Novel
Low
High
Cue Reversal - fMRI
Dobbins, Schnyer, Verfaellie & Schacter (2004) Nature

25. Is Object Priming Response Specific?
-15
Start
Switch
Return
Mean “Neural Priming”
-0.04
0.00
0.04
0.08
0.12
-0.02
0.02
0.06
0.10
PFC
Fusiform
.00
.10
.20
.30
PFC
Fusiform
Start
Switch
Return
Forgetting
Control
Dobbins, Schnyer, Verfaellie & Schacter (2004) Nature

26. Is Object Priming Response Specific?
-15
Relation to Behavior
Both fusiform and PFC “neural priming” scores predicted
behavioral priming scores, each accounting for unique variance.
PFC (not fusiform) neural priming predicted size of behavioral
slowing that occurred when cue was switched…suggests
that lack of activity is a marker of automaticity.

27. Is there a correlation between behavioral & neural priming?
Frontal
Temporal
Perceptual
-Dobbins et al. (2004)
-Maccotta & Buckner (2004)
-Lustig & Buckner (2004)
-Bergerbest et al. (2005)
-Golby et al. (2005)
-Oranfidou et al. (2006)
-Bunzeck et al. (2006)
-Turk-Browne et al. (2006)
-Carlesimo et al. (2003)
-Dobbins et al. (2004)
-Turk-Browne et al. (2006)
-later visual cortices

28. A multiple component model of priming
Form specific
Stimulus Specificity
Most
Least
Schacter, Wig & Stevens (2007). Curr Opin Neurobiol

29. A multiple component model of priming
-Amodal
-Priming across abstract representations
-Sensitive to changes in stimulus-decision mapping
Stimulus Specificity
Most
Least
Schacter, Wig & Stevens (2007). Curr Opin Neurobiol

30. A multiple component model of priming
-Amodal
-Priming across abstract representations
-Sensitive to changes in stimulus-decision mapping
-Most consistently correlated with behavior
Stimulus Specificity
Most
Least
Schacter, Wig & Stevens (2007). Curr Opin Neurobiol

31. Study Phase
For each of 3 runs at study, 144 shapes were presented (16 sets of 9 exemplars)
Each set alternated in spatial position to the right or left of fixation
Pres. Time = 2.5 sec
Nonstudied
Prototype
Exemplar
Exemplar
Instructions: remember each shape and side of the screen
Slotnick Schacter (2004) Nature Neuroscience

32. True recognition > False recognition
Ventral View
Time (sec)
% Signal change
0.1
0.2
0.3
-0.1
-0.2
-0.3 4 8 12 16
Left fusiform gyrus (BA18)
Old-hits
Related-false alarms
Early visual regions (BA17, BA18) LH
Old-hits > Related-false alarms X
Related-false alarms > Old-hits

33. Nature of visual area activity?
Time (sec)
% Signal change
0.1
0.2
-0.1
-0.2 4 8 12 16
Left fusiform gyrus (BA37)
Old-hits
Old-misses
New-correct rejections
Late visual regions (BA19, BA37)
Ventral View
* Old-hits > Old-misses should reflect conscious recollection
* Old-hits + Old-misses expected to reflect nonconscious activity
Time (sec)
% Signal change
0.2
-0.2 4 8 12 16
Left cuneus (BA18)
0.4
Early visual regions (BA17, BA18) LH
Old-hits > Old-misses
Old-hits + Old-misses

34. Line Orientation Task
*For each shape (at ‘study’ or ‘test’), speeded response whether internal lines sloped:
1) upward
2) downward
*Subjects were not informed that any shapes would be repeated.

35. Line Judgment Task: Old>Related
Ventral View
Left lingual gyrus (BA18)
Time (sec)
% Signal change
0.1
-0.1 4 8 12 16
Old
Related
0.2
* Early visual regions (BA17, BA18)
* No late visual region activity (BA19,BA37) LH
Old > Related X
Related > Old
Slotnick & Schacter (2006) Neuropsychologia

36. Line Judgment Task: Behavioral Results* *
980
970
960 ns
950
Reaction Time (ms)
940
930
920
910
Old
Related
New
* p < 0.05
Slotnick & Schacter (2006) Neuropsychologia

37. A multiple component model of priming
-Amodal
-Priming across abstract representations
-Sensitive to changes in stimulus-decision mapping
-Most consistently correlated with behavior
Stimulus Specificity
Most
Least
Schacter, Wig & Stevens (2007). Curr Opin Neurobiol