Learning or Boredom? Task Adaptation Effects in Sentence Processing Experiments.

Task adaptation, characterized by a progressive increase in speed throughout experimental trials, has been extensively observed across various paradigms. Yet, the underlying mechanisms driving this phenomenon remain unclear. According to the learning-based explanation, participants are implicitly learning, becoming more proficient over time. Conversely, a motivation-based view suggests that participants' drive wanes gradually, prompting quicker pace and reduced task engagement. These explanations offer distinct predictions. The learning-based view anticipates not only accelerated speed but also improved response accuracy. In contrast, the motivation-based view assumes that participants lose their focus, their pace increases, but their response accuracy tends to decline. The present study tests these implications in a series of six self-paced reading experiments investigating the interplay between reaction times, immediate recall, and trial order. Robust learning effects are documented. Participants not only read progressively faster during the experiments, but they also get better in responding. Moreover, an analysis of recall accuracy reveals systematic differences between different types of information, with nouns yielding substantially higher recall accuracy than adjectives. These findings are explained through attentional mechanisms: prolonged processing of specific words correlates with improved recall. Furthermore, the differential recall patterns are modulated by the task's question structure, with adjectives recalled more effectively in experiments with a higher proportion of adjective-targeting questions. This underscores participants' strategic allocation of attention to sentence components deemed crucial for task performance, highlighting the dynamic interplay between learning, motivation, and attentional mechanisms in task adaptation.