Consumer demand tests (animals)

Stylised responses of animals in consumer demand tests

Consumer demand tests for animals are studies designed to measure the relative strength of an animal's motivation to obtain resources such as different food items. Such demand tests quantify the strength of motivation animals have for resources whilst avoiding anthropomorphism and anthropocentrism.[1]

The test results are analogous to human patterns of purchasing resources with a limited income.[2][3] For humans, the cost of resources is usually measured in money; in animal studies the cost is usually represented by energy required, time taken or a risk of injury.[4] Costs of resources can be imposed on animals by an operant task (e.g. lever-pressing), a natural aversion (e.g. crossing water), or a homeostatic challenge (e.g. increased body temperature). Humans usually decrease the amount of an item purchased (or consumed) as the cost of that item increases. Similarly, animals tend to consume less of an item as the cost of that item increases (e.g. more lever presses required).[5][6]

Using consumer demand tests one can empirically determine the strength of motivation animals have for a definite need (e.g. food, water) and also for resources we humans might perceive as a luxury or unnecessary but animals might not (e.g. sand for dustbathing[7] or additional space for caged mice[8]). By comparing the strength of motivation for the resource with that for a definite need, we can measure the importance of a resource as perceived by the animals. Animals will be most highly motivated to interact with resources they absolutely need, highly motivated for resources that they perceive as most improving their welfare, and less motivated for resources they perceive as less important. Furthermore, argument by analogy indicates that as with humans, it is more likely that animals will experience negative affective states (e.g. frustration, anxiety) if they are not provided with the resources for which they show high motivation.[4]

Various other aspects of the animal's behaviour can be measured to aid understanding of motivation for resources, e.g. latency (delay) to approach the point of access, speed of incurring the cost, time with each resource, or the range of activities with each of the resources. These measures can be recorded either by the experimenter or by motion detecting software. Prior to testing, the animals are usually given the opportunity to explore the apparatus and variants to habituate and reduce the effects of novelty.

  1. ^ "Sherwin, C.M. Validating refinements to laboratory housing:asking the animals". Archived from the original on January 21, 2012. Retrieved September 11, 2012.
  2. ^ Lea, S.E.G., (1978). The psychology and economics of demand. Psychological Bulletin, 85:441–466
  3. ^ Dawkins, M.S., (1983). Battery hens name their price: consumer demand theory and the measurement of ethological "needs". Animal Behaviour, 31: 1195–1205
  4. ^ a b Dawkins, M.S., (1990). From an animal's point of view: motivation, fitness, and animal welfare. Behavioral and Brain Sciences, 13: 1–61
  5. ^ Duncan, I.J.H., (1992). Measuring preferences and the strength of preferences. Poultry Science, 71: 658–663
  6. ^ Sherwin, C.M., (1996). Laboratory mice persist in gaining access to resources: a method of assessing the importance of environmental features. Applied Animal Behaviour Science, 48: 203–214
  7. ^ Faure, J.M. and Lagadic, H., (1994). Elasticity of demand for food and sand in laying hens subjected to variable wind speed. Applied Animal Behaviour Science, 42: 49–59
  8. ^ Sherwin, C.M. and Nicol, C.J., (1997). Behavioural demand functions of caged laboratory mice for additional space. Animal Behaviour, 53: 67–74