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When making causal inferences, prior research shows that people are capable of controlling for alternative causes. These studies, however, utilize artificial inter-trial intervals on the order of seconds; in real-life situations people often experience data over days and weeks (e.g., learning the effectiveness of two new medications over multiple weeks). In the current study, participants learned about two possible causes from data presented in a traditional trial-by-trial paradigm (rapid series of trials) versus a more naturalistic paradigm (one trial per day for multiple weeks via smartphone). Our results suggest that while people are capable of detecting simple cause-effect relations that do not require controlling for another cause when learning over weeks, they have difficulty learning cause-effect relations that require controlling for alternative causes. 

Spacing presentations of learning items across time improves memory relative to massed schedules of practice – the well-known spacing effect. Spaced practice can be further enhanced by adaptively scheduling the presentation of learning items to deliver customized spacing intervals for individual items and learners. ARTS - Adaptive Response-time-based Sequencing (Mettler, Massey, & Kellman 2016) determines spacing dynamically in relation to each learner’s ongoing speed and accuracy in interactive learning trials. We demonstrate the effectiveness of ARTS when applied to chemistry nomenclature in community college chemistry courses by comparing adaptive schedules to fixed schedules consisting of continuously expanding spacing intervals. Adaptive spacing enhanced the efficiency and durability of learning, with learning gains persisting after a two-week delay and generalizing to a standardized assessment of chemistry knowledge after 2-3 months. Two additional experiments confirmed and extended these results in both laboratory and community college settings. 

Adaptive generation of spacing intervals in learning using response times improves learning relative to both adaptive systems that do not use response times and fixed spacing schemes (Mettler, Massey & Kellman, 2016). Studies have often used limited presentations (e.g., 4) of each learning item. Does adaptive practice benefit learning if items are presented until attainment of objective mastery criteria? Does it matter if mastered items drop out of the active learning set? We compared adaptive and non-adaptive spacing under conditions of mastery and dropout. Experiment 1 compared random presentation order with no dropout to adaptive spacing and mastery using the ARTS (Adaptive Response-time-based Sequencing) system. Adaptive spacing produced better retention than random presentation. Experiment 2 showed clear learning advantages for adaptive spacing compared to random schedules that also included dropout. Adaptive spacing performs better than random schedules of practice, including when learning proceeds to mastery and items drop out when mastered. 

What affects whether one person represents an item in a similar way to another person? We examined the role of verbal labels in promoting representational alignment. Three groups of participants sorted novel shapes on perceived similarity. Prior to sorting, participants in two of the groups were pre-exposed to the shapes using a simple visual matching task and in one of these groups, shapes were accompanied by one of two novel category labels. Exposure with labels led people to represent the shapes in a more categorical way and to increased alignment between sorters, despite the two categories being visually distinct and participants in both pre-exposure conditions receiving identical visual experience of the shapes. Results hint that labels play a role in aligning people's mental representations, even in the absence of communication 

Do people perceive shapes to be similar based purely on their physical features? Or is visual similarity influenced by top-down knowledge? In the present studies, we demonstrate that top-down information – in the form of verbal labels that people associate with visual stimuli – predicts visual similarity as measured using subjective (Experiment 1) and objective (Experiment 2) tasks. In Experiment 1, shapes that were previously calibrated to be (putatively) perceptually equidistant were more likely to be grouped together if they shared a name. In Experiment 2, more nameable shapes were easier for participants to discriminate from other images, again controlling for their perceptual distance. We discuss what these results mean for constructing visual stimuli spaces that are perceptually uniform and discuss theoretical implications of the fact that perceptual similarity is sensitive to top-down information such as the ease with which an object can be named.