Keep numbers in view: red-eared sliders (Trachemys scripta elegans) learn to discriminate relative quantities

Area of Science:

• Cognitive Ecology
• Comparative Psychology
• Ethology

Background:

• Numerical competence, specifically relative quantity discrimination, is an adaptive trait crucial for survival in unpredictable environments.
• While observed in humans, non-human primates, and birds, this capacity's prevalence in other vertebrate groups remains largely unexplored.
• Reptiles, as a diverse vertebrate class, offer a unique opportunity to investigate the evolutionary origins of numerical cognition.

Purpose of the Study:

• To investigate the capacity for relative quantity discrimination in the red-eared slider turtle (Trachemys scripta elegans).
• To determine if turtles utilize relative quantity or absolute quantity when making choices between stimuli.
• To provide behavioral evidence for numerical abilities in reptiles and infer potential evolutionary distribution.

Main Methods:

• Subjects (red-eared sliders) underwent training to differentiate visual stimuli associated with food rewards.
• Post-training, novel stimulus pairs were presented to assess choice behavior.
• Analysis focused on whether choices were based on relative numerosity or absolute numerosities.

Main Results:

• The majority of turtles successfully completed the initial stimulus discrimination training.
• During the testing phase, turtles demonstrated a preference for choosing based on relative quantity over absolute quantity.
• This indicates a sophisticated numerical processing ability in the tested reptile subjects.

Conclusions:

• This study provides the first behavioral evidence of relative quantity discrimination in the red-eared slider turtle.
• The findings suggest that the cognitive mechanisms for processing numerical information may be more widespread among vertebrates than previously assumed.
• Further research into reptile cognition can illuminate the evolutionary trajectory of numerical abilities across diverse taxa.