chapter 11 – 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 out

• We have already discussed an example of a cognitive experiment

• Identity learning (Sameness)– Train (MTS)

• RR+G-• GR-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 relationships.• There is no RF history of picking Blue following Blue • Seems more likely performance is the result of an understanding of “sameness”

– 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 memory?

– 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 retrieval

• 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– sports– musical instruments– write

• Explicit (declarative)– Knowing that you know (conscious awareness)– Episodic is clearly declarative

• the person is clearly aware of learning they experienced.

• 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

baited. • animal is confined in start area.

– Turn light on; then off to indicate which compartment was correct

– 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 Hunter’s?– Eliminates behavioral explanation for

retention• Face where you intend to go.• Animal has no way of knowing which key will be

correct– 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)

• DMTS – 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 conditions– 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 mazesSpatial 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 maze?– 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 chance

• Retrospective and Prospective Coding• How do the rats keep track of the arms of the

maze? – 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 arms.– 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 mistakes

• 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 mistakes

• 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-• GG+R-

– Phase 2 DMTS with cues• R-VR+G-• G-VG+R-• R-HITI• G-HITI

– Test • with forget cues

– R-HR+G-– G-HG+R-

• Compare to remember cues– R-VR+G-– G-VG+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

F-cues– 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 F-cues is novel• The novel (or surprising) cues could disrupt

performance

• The substitution procedure corrects for the above issues.• Substitution Procedure

– Phase 1 MTS• R R+G-• GG+R-

– Phase 2 DMTS with cues• R-VR+G-• G-VG+R-• R-HB+Y-• G-HB+Y-

– Test • with forget cues

– R-HR+G-– G-HG+R-

• Compare to remember cues– R-VR+G-– G-VG+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 demanding

• 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