Investigating capacity for sentience in Galliform birds and Molluscan invertebrates

Background:

For many years, the study of sentience was thought to be outside the scope of scientific research; the subjective experiences of animals were seen as inaccessible to objective scrutiny. But public and political concern for animal welfare is based on the assumption that many animals are sentient; that they have the capacity for feelings, and may, therefore, experience suffering. With the rise of consciousness science and affective neuroscience (the study of emotion-like, ‘affective’ states in animals), however, researchers have now begun to regard sentience as an important and tractable field of biological research (Birch et al 2020; Elwood 2022; Mason & Lavery 2022).

Recently, a number of different tests of sentience have been proposed, each of which assess animals’ capacities for particular types of decision-making that are believed to be dependent on consciousness in humans. But these tests vary greatly in terms of which species they are suitable for, and whether they tap equivalent decision-processes at a mathematical level of description. In the proposed PhD research, the student will undertake a series of studies to investigate the relationship between affective decision-making processes and sentience in animals.

Aims and objectives:

The successful student’s research will address the question of animal sentience by developing and refining novel methods for assessing and modelling decision-making within two groups of very different animals: Galliform birds (e.g. Gallus gallus domesticus; etc.) and Molluscs (e.g. Lymnaea stagnalis; Cornu aspersum; etc.).

The aim will be to develop novel experimental methods to assess affective, two-choice decision-making in a variety of animal species in order to model the decision-processes involved. We hypothesise that birds will use more complex decision-rules than molluscs and modulate their decision processes in different (e.g. more flexible) ways (e.g. using a greater variety of decision-parameters).

Methods:

The student will search for evidence of affective sentience in diverse phyla, in order to track potential markers of conscious affective states in decision-making.

Tasks will be based on existing experiments in which an affective (emotion-like) state is traded-off against another key motivational requirement (e.g. need for food). For example: a hermit crab is given the choice between staying inside a shell which produces electric shocks vs leaving the shell into a potentially dangerous environment, or a mouse is given the choice between remaining in a dimly-lit, CO2-filled compartment vs escaping to a brightly lit (aversive) compartment.

To date, such experiments have been used in a limited number of non-human species (Elwood 2019; Moody & Weary 2014). The experiments developed here will extend this species range, improve translatability (i.e. to enable cross-species comparisons) and increase the volume of data recorded in order to employ mathematical modelling analyses. Models of two-choice decision-making (e.g. diffusion model – Ratcliff & McKoon 2008), will allow much more complete analyses of the decision-process than previous behaviour-only studies. Specifically, they will allow assessment of: (i) the most appropriate model for describing each species decision-choices, (ii) similarities and differences between species in the parameters that modulate decision-making.

Key references:

Birch et al (2020) Dimensions of animal consciousness. Trends in Cognitive Sciences, 24(1), 789-801.

Elwood (2019) Discrimination between nociceptive reflexes and more complex responses consistent with pain in crustaceans. Philosophical Transactions of the Royal Society B., 374, 20190368.

Elwood (2022) Hermit crabs, shells and sentience. Animal Cognition 25, 1241-1257.

Mason& Lavery (2022) What is it like to be a bass? Frontiers in Veterinary Science 9, 788289.

Moody & Weary (2014) Mouse aversion to isoflurane vs carbon dioxide gas. Applied Animal Behaviour Science 158, 95-101.

Ratcliff & McKoon (2008) The diffusion decision-model. Neural Computation 20, 873-922.

Supervisors:

Dr Elizabeth Paul (Bristol), Dr Jo Edgar (Bristol), Dr Sarah Dalesman (Aberystwyth), Dr Vikki Neville (Bristol)

How to apply:

Please visit the Bristol Veterinary School website Funded 4-year PhD Scholarship Bristol Veterinary School University of Bristol for details of how to apply and the information you must include in your application. If your application is shortlisted, you will be invited to interview on or before 17^th January. Interviews will take place on Microsoft Teams on 29^th January.  Start date Sept 2025.

Candidate requirements: Standard University of Bristol eligibility rules apply. Please visit PhD Veterinary Sciences Study at Bristol University of Bristol for more information.

Contacts: please contact [email protected] with any queries about your application.

Please contact the project supervisor for project-related queries – Dr Elizabeth Paul: [email protected]