Lecture 4 - Animal memory

Question 1

Capacity of animal memory - Vaughan and Greene?

Answer 1

• large memory capacity shown in pigeons
• carried out a no. of experiments in which pigeons were required to peck on a key in response to the presentation of some stimuli, but withhold their response with other stimuli
• in one experiment they were shown photographs of everyday scenes
• they received a reward for pecking on the key in front of some of the photos, but not others
• were able to discriminate 320 photos = high capacity memory

Question 2

What is periodic time?

Answer 2

• refers to the ability of animals to respond at a particular time
• animals possess a circadian clock = internal clock which allows them to time the day

Question 3

Roberts 1965?

Answer 3

• put tape over the eyes of cock croaches
• found that they did have a periodic cycle of activity but it wasn’t 24 hours but instead was 23 and a half hours
• got shorter and shorter, about 15 hours

Question 4

Bolles and lorge?

Answer 4

• bred mice and let them develop in either a 19hr cycle or 29hr cycle
• they found it difficult to learn when food would be delivered
• seems they have a 24hr cycle internally which is innate and not learnt

Question 5

What is interval time?

Answer 5

refers to the ability of animals to respond on the basis of specific durations

Question 6

Church & Deluty 1977?

Answer 6

• trained rats to press on levers in a conditioning chamber
• if the interval between two tones was four seconds long then the rats gained a food reward for pressing on the left lever, while food was delivered if they pressed the right lever after an interval of 16 seconds

Question 7

Church and Gibbon 1982?

Answer 7

• in a different study Church & Gibbon exposed rats to different periods in which the lights were turned off in the conditioning chamber
• only when the lights were turned off for 4 seconds were presses on a lever rewarded
• the results of both of these studies showed that rats could remember the durations of various stimuli

Question 8

Number - Clever Hans?

Answer 8

• a horse that become famous for his ability to solve math problems
• would stop tapping his hoof when the correct no. of taps corresponded to the correct answer
• however it was revealed that it was due to the body language of the questioner
• relaxed posture = cue to stop tapping

Question 9

Number - Brannon & Terrace?

Answer 9

• showed that monkeys were able to remember the numerosity represented by particular stimuli
• the monkeys had to touch squares in numerical order, as shown by the number of dots, to gain a food reward

Question 10

Number - Rugani, Regain & Vallortigara?

Answer 10

• showed that five-day-old chicks are able to remember the numerical serial position of a baited food well, in a row of nine other unbaited wells
• the experimenters ruled out the possibility that the birds had simply learned the spatial location of the correct food well by rotating the row through 90 degrees and testing the birds from a new starting position

Question 11

Number - Pepperberg 1994?

Answer 11

• trained a parrot that could name, when asked, the number of coloured blocks he sees in front of him
• when we see a very short presentation of a number of items we are able to accurately name the number of items, even though we have not been able to count them
• there is a perceptual ability in humans called subitizing, in which we can name the number of items in tasks like this, but only up to a maximum of seven or eight items
• this happens to be the same number that Alex was able to count to, so perhaps we should be cautious about how he solved the problem

Question 12

Categories - Herrnstein, Loveland & Cable 1976?

Answer 12

• many species of animal have been shown to be able to learn and remember information about categories
• they showed pigeons a set of 80 different photographs, half of which contained pictures of trees
• the photographs were taken from a set of over 500 pictures, and eventually the pigeons were able to discriminate accurately between the two categories of slides
• the results of this study led Herrnstein et al. to propose that pigeons had the ability to acquire concepts, or categorise information

Question 13

What are the 4 explanations for categorisation?

Answer 13

1. innate categories
   - we are born with the ability to categorise
   - face recognition in humans is an e.g. of an innate category
   - doesn’t make sense for animals though
2. exemplar learning
   - this means the animal remembers every instance or exemplar of the category
3. feature learning
   - if a pigeon learns about the features that the rewarded slides have in common with each other then it will form a positive association with features that slides share
4. exemplar learning and stimulus generalisation
   - stimulus generalisation is when we show a strong conditioned response to items that are similar to the trained stimulus, but as similarity decreases responding drops off

Question 14

Short term memory?

Answer 14

lasts for short periods of time and concerns information about the immediate past

Question 15

Habituation?

Answer 15

• a reduction in responsiveness to a stimulus as a result of it’s repeated presentation
• is short-lasting and susceptible to interference

Question 16

Whitlow - rabbits?

Answer 16

• presented a loud tone to rabbits in a chamber and measured the change of blood flow in their ears in response to each presentation of the tone
• he found that on the first presentation (S1) there was a strong response, but on the second presentation (S2), after a 60 second delay, there was a weaker response
• if the interval was increased from 60 to 150 seconds the response to S2 was just as high as the response after S1

Question 17

Wagner?

Answer 17

• Whitlow’s work led him to explain habituation in terms of memory, saying that the offset of S1 will leave a decaying representation of itself
• the representation can be in one of three states: two active states, A1 and A2, and one inactive state, in which the memory is not modifiable and is unable to influence the animal’s behaviour
• in the A1 state the representation can be thought of as being at the centre of the animal’s attention
• as it decays, it moves to the A2 state, which can be thought to be at the periphery of the animal’s attention
• it then decays to the inactive state
• a representation in the A2 state cannot move to an A1 state before it has completed its decay to the inactive state
• once in the inactive state the representation can move to the A1 state

Question 18

Wagner’s model and habituation?

Answer 18

• if S2 is presented before the decay from A1 to A2 is complete – that is, within 150 seconds – and it matches the representation of S1, then habituation will be observed
• however, if the delay between S1and S2 is longer than 150 seconds, then no habituation is observed, which is what Whitlow found

Question 19

Can effector fatigue be an explanation for Whitlow’s data?

Answer 19

• if the physiological system that is responsible for overt behaviour is fatigued then it will not be able to respond to any stimulus within the period of fatigue
• Whitlow showed that Effector fatigue was not a good explanation for his results by changing the properties of the tone presented at S1 and S2
• while habituation was normal when the same tone was presented at S1 and S2, with a 60 second delay, there was no habituation if different tones were used
• since overt behaviour was not impaired, effector fatigue could be ruled out

Question 20

Can receptor fatigue be an explanation for Whitlow’s data?

Answer 20

• in this case, cells responsible for the reception of S1 might be fatigued after the offset of S1 and would therefore be less sensitive at the presentation of S2
• if the two tones presented at S1 and S2 are different then different receptors would be involved, but if the two tones at S1 and S2 are the same then the same receptors would be involved to process the two tones
• if these receptors are fatigued then they would be unable to respond appropriately at S2
• to determine whether Receptor fatigue could explain his results, Whitlow presented the same tone at S1 and S2, with a 60 second delay between the two
• mid-way through the delay, however, there was a 2 second distractor – a flashing light and a buzz near the eye
• the distractor disrupted habituation, producing dishabituation therefore ruling out receptor fatigue as an explanation for the original habituation results
• the distractor = retroactive interference

Question 21

Radial maze - Olton?

Answer 21

found that during the radial maze task memory seems to be more resilient to retroactive interference than in habituation

Question 22

Long term memory?

Answer 22

• large capacity and durability

Question 23

What are the 3 phases of LTM?

Answer 23

1. consolidation
2. retention
3. retrieval = animal forms a memory trace, stores information and acts on the memory when required

Question 24

Consolidation theories?

Answer 24

• place emphasis on the first 2 phases
• believe forgetting is due to an inadequate trace being laid down or to the passing of time
• Hebb 1949:
  -> memory depends on the virtually permanent formation of circuits of interconnected neurons
  -> consolidation and rehearsal is needed to complete these connections

Question 25

Retrieval theories?

Answer 25

• the formation of a memory trace is instantaneous and once it is formed it remains intact
• claims that forgetting is due to the animals inability to retrieve the information