Working memory is a system of limited capacity that holds a small number of mental contents (such as words, numbers, or objects) available for ongoing processing. As such, working memory is the blackboard of thought. Processing information in working memory involves selective access to some of its contents. For instance, when we add three-digit numbers, we need to selectively access first the ones, then the tens, then the hundreds, without at the same time forgetting the remaining digits. Selective access is the function of a focus of attention directed at working-memory contents. Thus, we can direct attention "inward" on the contents of our working memory just as we can direct attention "outward" to aspects of the perceived world around us. The question addressed in the project is whether attention directed to working-memory contents and attention directed to contents of perception (such as objects, or spoken words) uses the same or overlapping cognitive mechanisms. We test this through experiments that engage participants in a task involving continuous updating of working memory. People remember two or three numbers and update individual numbers through arithmetic operations. Thus, their focus of attention is constantly engaged with selecting one number and carrying out calculations with it. Occasionally, people will be interrupted by a perceptual event (e.g., a phone ringing or a letter flashed on the computer screen) and they have to respond to that event (e.g., by pressing a button to switch off the phone, or by making a quick decision whether the letter is an L or a T). The task to carry out in response to the perceptual stimulus will be designed so that it attracts one or another variety of perceptual attention (e.g., attention to a location in space, attention to an acoustic event, attention to a feature dimension such as color, etc). If attention to perceptual information overlaps with attention to working-memory contents, we expect an interruption of the continuous updating task. In particular, we expect that after the interruption task, attention will no longer rest on the last digit updated before the interruption. As a consequence, it should not matter whether the next arithmetic operation must be applied to the same digit as before the interruption or to another digit. The project will provide new insights into the mechanisms of attentional selection directed at perceptual input and at memory representations. In addition, it will provide knowledge about the circumstances under which a train of thought is interrupted by an environmental demand, and how well the mind can recover from such interruptions.