In situations in which multiple predictors anticipate the presence or absence of an outcome, cues compete to anticipate the outcome, resulting in a loss of associative strength compared to control conditions without additional cues. Critically, there are multiple factors modulating the magnitude and direction of such competition, although in some scenarios the effect of these factors remains unexplored. We sought to assess whether the relative salience of the elements in a compound of cues modulates the magnitude of the overshadowing effect in human predictive learning. Two separable categories (i.e., colors and symbols) were used in a predictive learning task. In Experiment 1, different groups of participants were granted with different time of exposure to a compound of cues belonging to different categories (color and symbol) to evaluate potential differences in the magnitude of overshadowing. Furthermore, we used posttest questionnaires to assess whether participants used either only one or both categories during training, and assessed if this impacted the magnitude of overshadowing. In general, overshadowing was not modulated by the time of exposition, except in the case of very short time of exposition with prominent learning about the most salient category. In Experiment 2, the relative salience of a category was biased via prior experience either with a biconditional discrimination or attending only the relevant category (either color or symbol). The previously relevant category was less prone to overshadowing, but not the alternative one. Results are discussed in light of attentional and configural theories of associative learning.In any domain of daily life and cognition, humans solve tasks and make decisions by using information that comes from multiple, different sources. It is quite obvious that we learn from previous experiences. We then use multiple sources of information to guide our behaviour in environments, make decisions about what is beneficial for us, and act in social situations (attributions, imitation). Most times however, not all information in the environment is useful. For example, if we eat fish and chips and later become ill, it is difficult to know which of the two made us ill, and people tend to select one or the other based on quantity. In fact, humans are particularly adept at selecting and learning from those sources which provide information about relevant outcomes. Hence, the idea of competition between different sources of information has been prominent in theories of learning. A wealth of data in the social sciences and psychology supports this assertion. Yet, the finding that multiple sources of information compete during learning is not ubiquitous. In some fields (i.e., spatial learning, category learning) and in experiments using animals, researchers have found facilitation (the opposite of competition) between multiple sources of information, and this has led to the development of specific theories that explain those findings, by assuming they are "exceptions". Thus, there are theories aimed at explaining competition, and theories aimed at explaining facilitation, but no consensus regarding the circumstances that lead to either of these opposite outcomes. Based predominantly on experiments conducted in nonhuman animals, Urcelay has recently hypothesized that competition and facilitation are two extremes of a continuum which is determined by multiple variables. The objective of this proposal is to test whether contiguity (that is, the temporal and spatial separation of events) is a critical determinant of these opposite findings. We predict that competition and facilitation are phenomena that can be observed across different tasks and domains of cognition. Therefore, we will test this general prediction across different learning preparations with increasing complexity. First, we wish to determine whether competition and facilitation are observed as a function of temporal separation between hypothetical food consumption and sickness in a predictive scenario such as the food-disease example mentioned above. The second objective is to extend these findings to an action-outcome task. Action-outcome learning underlies the sense of agency, free will and responsibility. We will investigate whether competition or facilitation are observed in a task in which participants' actions (i.e., press a button) and other environmental events (a signal) are presented simultaneously during learning. We will do this whilst manipulating the time between action and the outcome. We predict that when outcomes are presented soon after the action, stimuli will compete with action-outcome learning, but that the opposite will occur when outcomes are delayed. This is relevant to human behaviour because most of our actions are followed by delayed outcomes (e.g., saving for retirement; preparing for a child's birth). The final objective of this proposal is to investigate this prediction in spatial learning, which integrates the above mentioned objectives in a more complex and ecologically valid setting, whilst extending the prediction to spatial separation. Notably, in spatial learning both competition and facilitation have been observed, but the exact reasons for these discrepant findings have not been elucidated. In all three objectives, we will further investigate the psychological mechanisms (whether participants process different bits of information as separate elements, or as a whole) underlying competition and facilitation in these three scenarios. These findings have important implications for theories of learning, and for education.

Online data collection. Participants were recruited through Prolific.