Measures of Aversion

Question 1

Give examples of real-life scenarios involving aversive stimuli which must be investigated

Answer 1

Euthanasia of lab rodents Transport/handling of farm animals Conditions that lead to pain (not nociception) Pharmacology

Question 2

What technique is used to prevent having to re-use the aversive stimuli in a lab test?

Answer 2

Aversion learning - may be classical or operant avoidance

Question 3

What is classical aversion learning?

Answer 3

Conditioned supression

Question 4

What are the two types of instrumental avoidance learning?

Answer 4

Active and passive

Question 5

What is conditioned suppression?

Answer 5

Positively reinforced task is taught (operantly) eg. peck for food Inescapable aversive stimulus presented immediately after warning signal (classical conditioning)Extent to which baseline task is suppressed is taken as a degree of aversion

Question 6

Give an example of a baseline task used for humans to show classical conditioned suppression

Answer 6

moving disks from one spike to the next Salgado et al. 2000Conditioned stimulus = tone, Unconditioned stimulus = loud noise

Question 7

How is the suppression ratio calculated?

Answer 7

a/(a+b) a=rate of activity during CSb=rate of lever pressing prior to CS Ratio of 0.5 indicates no suppression

Question 8

What are the problems associated with using conditioned suppression as a measure of aversion?

Answer 8

Not ethical! Not sure why suppression occurs as doesn’t prevent aversive stimuli May be inappropriate for some speices Sensitivity in doubt - response may be all or nothing so no gradated Learned helplessness can occur

Question 9

Is conditioned suppression used by welfare scientists?

Answer 9

No, only learning theory investigation

Question 10

How does active instrumental avoidance work?

Answer 10

Animal trained to perform a response to avoid exposure to aversive stimulus NEGATIVE REINFORCEMENT consistency and speed of task performance indicates degree of aversion

Question 11

What are the problems associated with active instrumental avoidance techniques?

Answer 11

Species-specific responses to fear Animals may freeze Can only assess effects of immediate stressors (ie. not heat or subtle environmental changes)

Question 12

Give an example of active instrumental avoidance

Answer 12

Rutter and Duncan 1991 - hens run from one side of box to the other to escape suddenly inflated balloon Light predicted thisHens DID NOT learn this predictor

Question 13

What is PASSIVE operant or instrumental avoidance?

Answer 13

Animals learn not to perform a behaviour to avoid exposure to an aversive stimulus Punishment Consistency and speed of response inhibition indicates degree of aversion Most common in welfare science

Question 14

What is the commonest way of measuring aversion in welfare science?

Answer 14

Passive operant or instrumental avoidance

Question 15

Give four examples of passive operant avoidance

Answer 15

• Rushden 1996 - sheep run through a race and subjected to different treatments Latency measured (learnt not to perform the running through race response in order to avoid shearing or handling)- Zebra fish aversion to anaesthetics - put into test chamber and see where fish move to - moved out of MS222 and benzocaine, two agents identified that were non aversive - Makowska and Weary 2007,8,9 - rodent euthanasia agents - had to go down into a different chamber to get food - Nasr 2013 - testing for longer duration aversive states (keel fractures) - conditioned place preference/aversion

Question 16

What is necessary when measuring aversion?

Answer 16

A common currency to compare different aversive stimuli

Question 17

Who came up with criteria for a common currency method?What were they?

Answer 17

Abeyesinghe et al 2000 - repsonse compatible with species behaviour - method equally appropriate for all stressors being evaluated - method allows comparison over different time periods eg. immediate vibration stress v. heat stress - sufficiently sensitive to measure within-stressor (magnitude) and between - stressor differences - accurate, repeatable and robust

Question 18

What method allows multiple stressors to be compared at once?

Answer 18

Simultaneous choice

Question 19

Give 3 practical findings based on aversion measurement

Answer 19

Electro-immobilisation - more aversion than physical restraint, banned 1990 UK Sheep restraint - prefer to be in visual contact with other sheep and educating stockmen that animals remember poor/inconsistent handling for a long time Pharmacology and learning ability -most tests are not done to evaluate the aversiveness of a situation but rather assume the stimulus to be aversive