Investigating capacity for sentience in rodents and molluscan invertebrates

Background: Public and political concern for animal  and animal rights is based on the assumption that many animals are sentient; that they have the capacity for feelings, and may, therefore, experience suffering. But 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 private and inaccessible to objective scrutiny and experimental investigation. 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.

Aims and objectives:

This PhD will address the question of animal sentience directly, developing and refining methods for assessing sentience in animals. In recent years, a number of different tests of sentience have been proposed, each of which assess animals’ capacities for particular types of information processing (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 focus on conscious cognition or conscious affective states.

The aim of this PhD project is to search for evidence of affective sentience in diverse phyla, in order to begin the process of tracking the evolutionary origins of the use of both conscious and non-conscious affective states in decision-making.

Methods:

The sorts of tasks that will be used to investigate conscious/non-conscious affective states in decision-making are preference tests, affective ‘trade-off’ tests and ‘judgement-bias’ tests. The student will design and develop translational paradigms that allow similar assessments to be made in very different species; then, using established mathematical models of decision making, the components of the decision processes of these animals will be compared. The species to be studied will be rodents (Rattus norvegicus), whose emotional/affective systems and decision-making processes are already well-studied within affective neuroscience, and molluscs (Lymnaea stagnalis; Cornu aspersum

). In recent years, invertebrates have gained significant attention in terms of whether they are sentient and possess consciousness, but methodology is currently lacking to effectively allow direct comparison with species already deemed sentient. A key goal of this PhD research will be to develop methods that enable these sorts of comparisons.

Key references:

Brown, S.A.B., Birch, J. & Paul, E.S. (2024) To test the boundaries of consciousness, study animals. TRENDS IN COGNITIVE SCIENCES 28(10), 874-875.

Mendl, M.T. & Paul, E.S. (2020) Animal affect and decision-making. NEUROSCIENCE AND BIOBEHAVIORAL REVIEWS 112, 144-163.

Paul, E.S., Sher, S. Tamietto, M., Winkielman, P. & Mendl, M. (2020) Towards a comparative science of emotion: Affect and consciousness in humans and animals. NEUROSCIENCE AND BIOBEHAVIORAL REVIEWS 108, 749-770.

Supervisors: Dr Liz Paul, Dr Sarah Dalesman, Prof Mike Mendl

Start date: Sept 2025

How to apply: See How to apply – SWBiosciences Doctoral Training Partnership

Candidate requirements:

The successful candidate is expected to have a background in zoology, biological sciences or experimental psychology. An existing interest in/experience of evolutionary biology and/or sentience will be advantageous but not essential. They will learn about animal behaviour and cognitive science, the design and running of decision-making tasks, mathematical modelling, animal care, and the experimental and philosophical challenges facing contemporary sentience research.

See Eligibility – SWBiosciences Doctoral Training Partnership.

Standard University of Bristol eligibility rules for PhD admissions also apply. Please visit PhD Veterinary Sciences

Contacts: Contact the lead supervisor e.paul@bristol.ac.uk if you have queries about the project. For queries about the SWBio DTP scheme contact swbio-dtp@bristol.ac.uk