Remembering

1
Remembering

• Animal Cognition
• Keith Clements

2
Aims

• To examine methods which can tell us about other
  species short-term and long-term memories their
  capacities and duration.
• To examine whether other distinctions, e.g.
  between implicit and explicit memory, can be
  observed in other species.

3
introduction

• Learning shows retention of information
• E.g. Jennings (1906)
• stentor-unicellular organism, retracts into tube
  when threatened
• response habituates to repeated jets of water
• behaviour modified by experience

4
Short term memory

• Limited capacity duration
• in humans about 7 items for seconds-minutes
• Methodology
• Radial Maze
• Are recently-visited arms revisited?
• Delayed matching to sample
• stimulus shown, after a brief retention period 2
  or more similar stimuli shown

5
Cont..

• Capacity
• In a radial arm maze, rats rarely return to
  previously visited arms. Above chance level with
  17 arms (Olton et al., 1977)
• Duration
• Beatty Shavalia (1988) removed rats after first
  4 choices. Replaced 4 minutes to 24 hours later.
  Still avoided visited arms up to 4 hours later.
• DMTS usually 5-10 seconds in pigeons, up to 2
  minutes in monkeys

6
Forgetting from short-term memory

• Interference
• Proactive vs retroactive interference
• e.g.
• in the radial maze repeated testing leads to
  reduced performance due to PI
• In the DMTS changing conditions between
  presentation of the sample and the test stimuli
  impairs performance due to RI (Grant Roberts,
  1976)

7
Long term memory

• Unlimited regarding both capacity and time
• food storing birds
• Clarks nutcracker 33000 pine nuts in 6000
  places in late summer-winter spring need to
  find these
• Cowie et al. (1981) gave radioactively labelled
  sunflower seeds to marsh tits. Birds remembered
  the location, added seeds were less likely to be
  retrieved.

8
Cont.

• Balda Witschko (1995)
• pigeons
• trained to find food hidden in 1 of 8 plastic
  sand-filled cups
• could remember which one had seed for up to 10
  months
• no difference if tested hours or days after
  original training
• Better than human memory?
• Maybe, but visual memory may be better than we
  assume
• E.g. see
• http//www.quirkology.com/UK/Experiment_totalRecal
  l.shtml

9
Different types of LTM

• In humans we can distinguish between
• episodic and semantic memory
• Memory for events versus general knowledge
• explicit and implicit memory
• Conscious, deliberate recall versus evidence of
  memory without conscious awareness.
• Without self-report data it may be difficult to
  distinguish these in other species.

10
Hampton (2001)

• Delayed Matching to Sample Test
• Rhesus monkeys chose whether or not to take the
  test for a favoured reward.
• Opting out of the test gave a less desired
  reward.
• Probe memory tests revealed monkeys were more
  accurate when they had chosen to take the test.

11
Conclusion

• Several types of memory exist. There are many
  similarities between animal and human
  performance.
• Abilities vary between species, related to their
  ecological niche.
• Careful design is needed to draw conclusions from
  performance about memory.

12
Reading

• Chapter 6 in Wynne covers todays topic
• There are notes from a lecture on memory
  available online at http//www.people.ex.ac.uk/SEG
  Lea/psy2001/T5memory/
• Theres a gallery of photos of radial arm mazes
  at http//www08.homepage.villanova.edu/michael.bro
  wn/