Angélique Roquet, winner of the thesis prize of Aix-Marseille University 2020

Her Master-2 internship at LPC helped her to develop her interest in behavioural sciences and it was in this perspective that she continued her PhD, still with Professor Patrick Lemaire (LPC).
Her PhD was entitled : “Cognitive mechanisms involved in numerosity comparison : developmental studies”. The speciality of her PhD director is mathematics work, of a fairly complex degree. With her desire to work on normal and pathological ageing, she proposed to work on the perception of numbers.

Before going any further, a little clarification is required!

What is numerosity?

The concept of numbers covers a great variety of contents. Our education has accustomed us to numerical symbols: numbers written in base 10 using Arabic numerals, such as “1053”, or expressed using number names such as “one thousand fifty-three”. However, cognitive psychology shows the importance of the non-symbolic perception of numbers, where the quantity 13 can be presented in the concrete form of a 13-points cloud or a sequence of 13 sounds. The number is here treated as the property of a pattern, which is often described in the technical term of numerosity. Learn more about it…

The aim of this PhD was to understand the cognitive mechanisms involved when we compare numbers.

She has focused on several cognitive mechanisms such as specific, perceptual, and general cognitive mechanisms. All these mechanisms are involved in number comparison tasks that she studied from childhood to normal ageing, but also during pathological ageing in Alzheimer’s patients.

With her PhD director, Angélique chose to respond to her hypothesis by conducting a Life-span study.

This type of psychological studies seeks to understand how mental processes, behaviours and performances of individuals change during childhood and adulthood.

To start this project, Angélique had to create a new experience, also known as a “task”. It is represented in the image below:

There are two collections of points presented on the screen. Participants must say which collection contains the most points, and must answer as quickly as possible.

For this cognitive psychology experiment the important thing is to create “conflicts”. These conflicts are situations with perceptual traps, based on misleading visual parameters.

Angélique Roquet then confronts these conflict situations by comparing them with more intuitive situations. The example of an intuitive situation: a collection where a lot of points occupy a lot of space.

After conducting a few pilot studies to ensure that her “task” was working well, she was able to work on these 4 types of audiences: children, adults, healthy older adults and Alzheimer’s patients.

To complete her study, she made the test accessible on the internet to carry out a “Big Data” study: 1200 participants of all ages!

Angélique has always been sensitive about the topic of ageing, as she feels that the elderly are often a forgotten category of the population. In her PhD, she studied a representative population  of a form of pathological ageing: patients with Alzheimer’s disease. With this in mind, she developed an academic collaboration with the neurologist Bernard Michel, Head of the Department of Behavioural Neurology (SNC) at Sainte Marguerite Hospital.

The study of Alzheimer’s patients required adaptive strategies. The tests are carried out on the computer, so Angélique has created joysticks to make it easier for the patients to perform the test. Despite this, a small group was not always able to carry out the test autonomously. Angélique therefore added a “help” variable to her experiment, to correctly interprete her data.

Select participants

Determining the level of understanding of Alzheimer’s patients is not easy. It is possible to refer to the stage the disease has reached, which corresponds to the degree of degradation of the patient’s hippocampus.

 “In very simplified terms, the more ” cheese holes ” are observed in the hippocampus, the more advanced is the stage of the disease”.

But in practice, categorising patients was much more complex. Indeed, some late-stage patients had a comprehension ability adapted to the experience, while some early-stage patients showed a comprehension ability that was too altered to perform the test. Although standardised by the neuropsychological tests carried out at the hospital, the results of the test show a high degree of inter-patient variability.

During her 3-year PhD, she conducted more than 120 tests on Alzheimer’s patients. She admits that her skills in neurosciences have helped her to work on this population, especially through exchanges with doctors or by interpreting MRI-type examinations. But it is her relational skills that have helped her to develop a climate of trust with the patients, contributing to the success of the test.

The data collected during his PhD research show that the estimation of numerosity is based on a combination of mechanisms! Especially strategic mechanisms: the participants used several strategies based on the physical characteristics of the collections of points (the pattern).

Then, she revealed that the estimation of numerosity was altered by Alzheimer’s disease, and that the origin of this decline might derive from a deficit of “specific mechanisms”, rather than “general cognitive mechanisms”.

The results presented in Angélique’s thesis make possible to specify the involvement of cognitive mechanisms in the estimation of numerosity, but also their evolution during development and during normal and pathological ageing, based on the Life-span study.

What she particularly highlights is the innate character of our perception of quantities.

After all, other animals also have this character. Predators will attack a solitary animal rather than a large herd. In Alzheimer’s patients, even at very advanced stages of brain damage, there are still evidence of this innate character!

After a position as ATER (Attachée Temporaire d’Enseignement et de Recherche) at Aix-Marseille University, she is now doing her post-doctorate at the University of Lausanne (UNIL), in the Institute of Psychology. Her research focuses on social factors that influence the behaviour of older people towards successful ageing. More concretely, why do some people age better than others and according to what factors?

In her career, she has always wanted to work around ageing and she has done so with different tools according to her past experiences: sometimes using neuroscience, sometimes using behavioural and cognitive psychology tools.

She would like to continue along this path and see research evolve into more interdisciplinary collaborations, because for her :

“Everything complements one another !”