Arbitrary acquisition of associations in a delayed conditional discrimination task (DCD) by young domestic chicks

The notion of working memory (WM), defined as the ability to maintain a body of information online for a short period of time, is a fundamental skill in everyday life as it enables us to string together thoughts and ideas and to plan actions toward our current goals. WM has recently been referred to as "the blackboard of the mind" and has been acknowledged as a crucial prerequisite in the conception of consciousness. WM recently became a main focus in the ethology and comparative psychology research fields because it represents one of the only measurable conscious memory systems since its contents are strictly attention-dependent. The study of WM in animals allows us to better understand and identify their subjective experiences. Lately, WM has been suggested as a diagnostic feature of conscious awareness, which represents a main challenge in the research field as the private nature of consciousness and our unavoidably anthropomorphic perspective makes it a primary riddle to evaluate. WM has long been analysed in different types of delayed response tasks, characterized by a temporal gap between stimulus and response. The most classic delayed response is the delayed match-to-sample task or DMS. However, the most classic procedures used to assess WM are susceptible to impediments such as the occurrence of mediating behavior to select the correct response giving rise to the debate about whether WM is being used or not. The present study focuses on a recently developed delayed response task called delayed conditional discrimination task or DCD, designed to better deal with these issues, applied in days-old domestic chicks (Gallus gallus). These animals represent one of the ideal models in cognitive and perceptual analysis, as well as an optimal representative reference for the neurocognitive complexity of the avian taxa. In this task, chicks will first experience a Conditional Cue, either a black or white panel. Chicks will then be asked to choose between three alternative Choice stimuli (a yellow, blue, or green box) to find a food reward. Two of these stimuli will alternately contain the reward, accordingly to the specific Conditional Cue just encountered, while the third one is always empty and represents a distractor stimulus. chicks must therefore learn an arbitrary conditional rule between Cue and Choice stimuli to effectively perform the task. In this study, we will analyse and discuss the results of this first procedure and afterward suggest a set of possible alternative procedures or refinements to potentially enhance the chick’s performance in the task. To truly compute WM we have to obstruct mediating behaviour usage to the fullest extent and the DCD procedure is shown to be the best delayed response task to do so. Hence, offering further chances to venture into the investigation towards a better understanding of what can finally be thought of as working memory, a cornerstone of the rational mind.