Investigating the relationship between personality and cue-based learning in the three-spined stickleback (Gasterosteus aculeatus)

Abstract

Understanding how individuals respond to novelty is important in the study of both personality and cognition. However, Novelty is still often viewed as a binary scale of novel or familiar, despite the fact that how an animal interprets novelty
can vary significantly and potentially impact survival. I examined how varying the type and degree of novelty by changing object identity and spatial location affected behavioural responses, to assess whether and how individuals alter their
behaviour as stimuli shift from novel to familiar. The majority of research to date that aims to link personality and cognition often only assesses the repeatability of personality and when cognitive repeatability is included it is often across different contexts which may not always assess the same trait. This thesis aims to address these limitations by evaluating both the repeatability and contextual relevance of personality and cognitive traits in three-spined sticklebacks (Gasterosteus aculeatus), across repeated trials and tasks. By doing so, it aims to better understand the consistency and flexibility of individual behavioural strategies and how these relate to cognitive performance. In Chapter 2, I examined how sticklebacks perceive novelty by manipulating object identity and spatial location in a novel object test. Fish were presented with one of four experimental conditions across four trials: same object in same location, same object in different locations, different objects in same location, or different objects in different locations. While emergence latency was shortest when both object and location changed, indicating an attraction to compound novelty, subsequent exploratory behaviours did not differ across treatments. Responses to the objects were highly repeatable regardless of novelty condition, suggesting that while initial responses to novel stimuli may be sensitive to changes in both object
identity and location, subsequent exploratory behaviours are primarily driven by stable individual differences. In Chapter 3, focused on cognitive performance in two associative learning tasks. Fish were required to locate a food reward using a visual landmark. While all fish experienced the same setup, three distinct learning strategies emerged: a group that followed the landmark successfully in both tasks (Learnt 1+2), a group that succeeded only in the first task (Learnt 1), and a group that did not meet the criterion in either task (Neither). Despite differences in learning accuracy and decision latency, all groups reached the food in similar times. This indicates that cue-following and exploratory strategies can be equally efficient under certain conditions. Furthermore, some fish switched strategies when the landmark changed, suggesting flexibility influenced by prior experience. These findings support the idea that learning success should not be defined solely by meeting arbitrary criteria and highlight the value of including individuals that fail to meet such benchmarks, as they may reveal alternative, ecologically relevant strategies. In Chapter 4, I assessed the repeatability of personality traits using two open field tests and three novel object trials conducted before and after the learning tasks discussed in Chapter 3. Fish were tested twice in an open field test and three times in a novel object test to assess personality traits such as boldness, neophobia, and exploration. Boldness scores from the open field and novel object tests were significantly correlated, indicating this may be a behavioural syndrome or measuring the same trait in different contexts. While no significant differences in personality traits were found between the three learning strategy groups, boldness was positively associated with cognitive performance within the Learnt 1+2 group. Bolder individuals reached learning criterion in fewer trials, made faster and more accurate decisions, and located food more quickly. In contrast, personality traits did not strongly relate to performance in the Learnt 1 or Neither groups, suggesting that the relationship between personality and cognition depends on the strategy used and the learning context. Overall, these findings show that while both personality and cognition can be consistent within individuals, the relationship between them is shaped by context. Boldness appeared beneficial in structured tasks where learning depended on repeated cues, but this advantage did not extend to all learning strategies. These results highlight the importance of moving beyond binary measures of cognitive success and instead recognising the diversity of strategies animals use to solve problems. By incorporating multiple behavioural measures and considering how individuals flexibly adapt to changing conditions, this study offers a more comprehensive understanding of how personality and cognition interact. It adds to growing evidence that successful behaviour may depend not only on consistency,
but also on the capacity for behavioural flexibility in dynamic environments.

Date of Award	2024
Original language	English
Awarding Institution	Aberystwyth University
Supervisor	Otar Akanyeti (Supervisor) & Sarah Dalesman (Supervisor)