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) • 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 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 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 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 • G  G+R – Phase 2 DMTS with cues • R-V  R+G • G-V  G+R • R-H  ITI • G-H  ITI – 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 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 • G  G+R – Phase 2 DMTS with cues • R-V  R+G • G-V  G+R • R-H  B+Y • G-H  B+Y – 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 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