Comparative Cognition 1: Memory Mechanisms

Chapter 11 – Comparative Cognition 1: Memory Mechanisms
• Outline
– What is Comparative Cognition
– Animal Memory Paradigms
• Working and Reference Memory
• Delayed Matching to Sample
• Spatial Memory in mazes
– Memory Mechanisms
• Retrospective and Prospective Coding
– Forgetting
• Proactive and Retroactive Interference
• Retrograde Amnesia
• Directed Forgetting
• Chapter 11 - Animal Cognition 1:
Memory Mechanisms
• What is Comparative Cognition?
– Zentall (1993)
– Animal Cognition is often best understood by
explaining what it is not.
• Learned behavior that is left after simpler
associative-learning explanations have been ruled
• We have already discussed an example of a cognitive
• Identity learning (Sameness)
– Train (MTS)
• RR+G• GR-G+
– Test
• B B+Y• Y B-Y+
• Notice the test involves novel stimuli
– This is often an important test in cognitive studies
• It makes it difficult to explain performance in test based on S-R –O
• There is no RF history of picking Blue following Blue
• Seems more likely performance is the result of an understanding of
– A cognitive rule
» Pick the thing that looks the same.
What is Comparative Cognition? Continued
• Domjan
– Theoretical constructs and models used to
explain aspects of behavior that cannot be
readily characterized in terms of simple S-R
or reflex mechanisms.
• Key feature
– Always adopt the simplest possible explanation
What is Comparative Cognition? Continued
• Must carefully avoid anthropomorphism
• Morgan’s Canon
– In no case may we interpret an action as the outcome
of a higher psychical faculty, if it can be interpreted as
the outcome of the exercise of one that stands lower
in the psychological scale.
– At first the allure is weak; there is a vague yearning
and a mild agitation. Ultimately, the strength of desire
grows irresistible; its head turns sharply and it skitters
across the uneven floor to caress the objects of its
affection with consummate rapture
• Coin drawn to a magnet
• There are more parsimonious explanations for this behavior
– Clever Hans
What is Comparative Cognition? Continued
• Often involves models of mental activity
– The internal clock (chapter 12)
• A model for how a biological clock might work
– Mental Representations
• What is the nature of a memory?
– It is not just a snap shot.
– It is some how changed to a neural code
– What is the nature of that code?
• Animal Memory Paradigms
• What is the difference between learning and
– The main difference is how we study each.
• Study Learning
– We vary aspects of acquisition
– Hold retention interval and retrieval variables constant
• Study Memory
– Hold acquisition constant
– Vary retention intervals or variables related to
• Types of memory
• Short term memory
– the phone number for pizza place
• Long term memory
– Episodic
• Picture yourself there (the episode)
– What did you have for dinner last night?
– What were you doing when you heard about the World Trade Center?
» Flash bulb
– Semantic
• Facts about the world
– Who was the first president?
– What year were you born?
– Procedural
• How to do things
ride a bike, drive, swim
musical instruments
• Explicit (declarative)
– Knowing that you know (conscious
– Episodic is clearly declarative
• the person is clearly aware of learning they
• They have a conscious memory for it.
– Semantic is as well
• You know that-you-know the year you were born
– Clive Wearing had no episodic memory at all
» Still knew he had a wife and kids
» No memory of spending time with them
• Implicit (nondeclarative or procedural)
– This is learning that you are not consciously
aware of.
• illustrated by priming experiments
• Also H.M.
– Mirror drawing task
• Also Clive Wearing
– Piano
– Much of the Pavlovian and Instrumental research
we have discussed would fall under procedural
• We will discuss animal models of Episodic memory in
Chapter 12
• Working Memory and Reference Memory
– another distinction that has received a lot of research interest in
comparative cognition
Reference Memory
– Long-term retention of information necessary for the successful
use of incoming and recently acquired information
• The rules of the game
• Working Memory
– Short-term information
• What did I just do?
• Cooking
– General recipe
• rules for making the dish
– Keep track of where you are
• What have I already done
• Walter Hunter (1913).
– Rats, dogs, and raccoons.
– Light indicates which of three compartments are
• animal is confined in start area.
– Turn light on; then off to indicate which compartment was
– They are not allowed to choose for various
lengths of time.
• Rats - 10 seconds.
• Racoons – 25 seconds
• Dogs – 5 minutes.
– Reference Memory?
– Working Memory?
• Problem with the study
• Matching-to sample
– Simultaneous
– Delayed
• Why is this technique better than
– Eliminates behavioral explanation for
• Face where you intend to go.
• Animal has no way of knowing which key will be
– Left vs. right = 50%
• What affects an animals memory in a
DMTS experiment?
• 1) nature of the sample stimulus affects
DMTS performance
– Lines and shapes
– Colors
• 2. Sample Duration?
– Grant (1976)
– 4 colors R,G,B,Y
– Each trial begins with white center key
» Warning stimulus
– Peck  turns to sample (i.e., Red)
» Stays on for different durations
» 1,4,8, or 14 s
• Test with Delays (retention intervals)
– 0, 20, 40, or 60
•Results (Figure 11.2)
•trace-decay hypothesis (Roberts & Grant, 1976).
•A simple idea, but clearly too simple.
• 3) Similarity between training and testing
– Instruction hypothesis (Zentall)
• What happens if animals are trained with a
particular delay and tested with others?
– Sargisson and White (2001).
• Train with 0, 2, 4, or 6 s delays.
• Test with 0, 2, 4, 6, 8, and 10 s delays.
•Figure 11.3
•0 – normal forget curve
•2 – forget curve does not start until 4 s
•4 – forget curve does not start until 6 s
•6 – no forget curve.
•What does this say about forget curves?
•Not just trace-decay
•Similarity between training and testing conditions are important
Spatial memory in mazes
Spatial memory in mazes
Spatial memory in mazes
Morris Water Maze
• Train in a room with external cues
– Door
– Pictures
– Light gradients
• Platform always in the same location
– Release from 4 different locations
• Randomly
– North, South, East, West
– Test?
• Escape latency (figure 11.4)
• Probe trials
– Path analysis.
• Probe trial mouse
• Spatial memory in the Radial arm maze
– Olton and Samuelson (1976)
• Food at end of each arm
– Or a subset of arms
• Reference Memory?
• Working Memory?
• You-tube vids of 8 arm maze
– Normal mouse
– Knockout mouse with memory probs
• How do the rats behave in radial arm
– Not a set sequence
– No strategy
– No odor cues
– They can handle long delays
• Let them choose four arms – four hours later they
choose the other 4
• Even after 24 hours they are performing above
• Retrospective and Prospective Coding
• How do the rats keep track of the arms of the
– Retrospective
• keep track of where they have been
– Prospective
• keep track of where they are going
• Cook, Brown, and Riley (1985)
• 12 arm maze
– Let rats choose 1, 2, 3, 4, 5, 6, 7, 8 , 9, 10, 11
– Remove the rat for 15 minutes
– Put them back in and complete the maze.
• retrospective memory
– memory load would start out low
– increases with arms visited
– having a heavy memory load, should lead to more
• predicts few errors after 1 choice
• many errors after 11 choices.
• prospective memory
– Memory load starts out high
• Have 11 arms still in memory
– Decreases with arms visited
– having a heavy memory load, should lead to more
• Predicts many errors after 1 choice
• Few errors after 11 choices
• These predictions are in direct
contradiction to one another.
• What do rats do?
• People?
• Forgetting
– Why does memory sometimes fail?
• Proactive and Retroactive interference
• Proactive interference
– Previous memories disrupt current memory
– Where did I park my car today?
• Retroactive interference
– New memories disrupt old memories
• Cumulative exams?
• Phone number from last apartment?
– Address?
• Amnesia
– Anterograde
• Unable to form memory for events that occurred after
the injury
– Retrograde
• Loss of memory for events prior to injury
• Squire’s electroconvulsive shock study
– Indicates that memories are vulnerable for an
exceptionally long time
• 1 year old memories were especially vulnerable
– Older memories were relatively unaffected
• Implies some active processing of memory (memory
consolidation) over an extended period of time.
• Directed Forgetting
– It is known that humans can exert cognitive
control over memory.
– Give a list of words to subjects to remember
• Tell them “okay – that was just practice. Forget about
that list and get ready for the real list”
• After a retention interval you tell them that you lied.
– Please write down as many words from the original list that
you can
• Compare to a group told to remember the list.
– Memory for the list is much poorer for those told
to forget.
• Perhaps because they did not initiate memory
maintaining strategies (rehearsal)
• Can animals exert cognitive control over memory?
• Omission Procedure
– Phase 1 MTS
• R R+G• GG+R-
– Phase 2 DMTS with cues
– Test
• with forget cues
– R-HR+G– G-HG+R-
• Compare to remember cues
– R-VR+G– G-VG+R-
– Result?
• Good performance on R-cued trials
• Poor performance on F-cued trials
• Problems with Omission Procedure?
• Roper and Zentall (1993)
– 1. no response requirement following F-cues
• Pigeons are not used to making a choice following
– Thus, disrupts responding in test
– 2. no RF following F-cues.
• F-cue could act as a conditioned inhibitor
– Thus, disrupt responding in test
– 3. Presentations of comparisons following Fcues is novel
• The novel (or surprising) cues could disrupt
• The substitution procedure corrects for the above issues.
• Substitution Procedure
– Phase 1 MTS
• R R+G• GG+R-
– Phase 2 DMTS with cues
– Test
• with forget cues
– R-HR+G– G-HG+R-
• Compare to remember cues
– R-VR+G– G-VG+R-
– Result?
• Good performance on all trials
• No evidence for directed forgetting
• Compare the human situation to that of the pigeon
– Maintaining a bunch of words in memory is
• Difficult to do
– The pigeons do not have nearly the same demands
• one sample to remember
– Red or Green
– There may be little cost to remembering regardless of the trial type.
• What if we increase the memory demand?
– Reallocation experiment
• Roper, Kaiser, and Zentall (1995)
• Train the pigeons with F-cues that they have to remember
– If they have to reallocate memory to the F-cue perhaps it will
disrupt memory for the original sample

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