A multimodal dual task experiment that contributed to the original development and tuning of the EPIC cognitive architecture is revised and revisited with the collection of new high fidelity human performance data, most notably detailed eye movement data, that reveal the complex overlapping of perceptual and motor processes within and between the two competing tasks. The data permit a new detailed evaluation of assumptions made in previous models of the task, and contribute to the development of new models that explore opportunities for overlapping visual-perceptual, auditoryperceptual, ocular-motor, and manual-motor activities. Three models are presented: (a) A hierarchical task-switching model in which each task locks out the other; the model explains reaction time but does not account for eye movement data. (b) A maximum-perceptual-overlap model that maximizes parallel processing and predicts the trends in the eye movement data, but performs too quickly. (c) A moderately-overlapped model that introduces task-motivated constraints and predicts both reaction time and eye movement data. The best-fitting model demonstrates the complex taskconstrained interleaving of perceptual and motor processes in a time-pressured dual task.

Abstract. Over their lifetimes, intelligent agents gain knowledge that may be pertinent to their decisions about acting in the world. One goal of memory system research is to develop the optimal set of encoding, storage, and retrieval mechanisms that will harness this experience to facilitate rational decisions. In this paper, we propose a direction of empirical, computational research that seeks to better understand the behavioural dynamics that arise when an agent endowed with long-term memory is situated in a task, by determining which properties of task and characteristics of memory systems are responsible for which aspects of behaviour. 1 We propose preliminary taxonomies for task and memory spaces, and also propose metrics for systematic evaluation of memory systems. 1

How do people interleave attention when performing multiple tasks, such as writing a paper while listening to music, or dialing a phone number while driving a car? A variety of cognitive models and architectures have been used to understand this interleaving process (e.g., Howes,

How do people interleave their attention when performing multiple tasks, such as dialing a phone number while driving, or checking e-mail while writing a paper? To investigate these issues a variety of modeling frameworks

Can people multitask optimally? We use a dual-task paradigm in which participants had to enter digits while monitoring a randomly moving cursor. Participants earned points for entering digits correctly and were docked points if they let the cursor drift outside of a target area. The severity of the tracking penalty was varied between conditions. Participants therefore had to decide how long to leave the tracking task unattended. As expected, participants left the tracking task for longer when the penalty was less severe and also when the cursor moved less erratically. To test whether participants were adjusting their behavior in an optimal manner, observed behavior was compared to a prediction of the optimal visit duration for each condition. Overall, the degree of correspondence between the observed behavior and the predicted optimum was very good, suggesting that people can multitask in a near optimal fashion given explicit feedback on their performance.

This paper investigates mechanisms of short-term memory involved in human sentence processing, focusing on how short-term memory functions are realized and constrained in establishing certain linguistic dependencies. We specifically examine a cue-based retrieval approach to short-term memory (Lewis et al. 2005, 2006) which assumes that a

Many comprehension theories assert that increasing the distance between elements participating in a linguistic relation (e.g., a verb and a noun phrase argument) increases the difficulty of establishing that relation during on-line comprehension. Such locality effects are expected to increase reading times and are thought to reveal properties and limitations of the short-term memory system that supports comprehension. Despite their theoretical importance and putative ubiquity, however, evidence for on-line locality effects is quite narrow linguistically and methodologically: It is restricted almost exclusively to self-paced reading of complex structures involving a particular class of syntactic relation. We present 4 experiments (2 self-paced reading and 2 eyetracking experiments) that demonstrate locality effects in the course of establishing subject–verb dependencies; locality effects are seen even in materials that can be read quickly and easily. These locality effects are observable in the earliest possible eye-movement measures and are of much shorter duration than previously reported effects. To account for the observed empirical patterns, we outline a processing model of the adaptive control of button pressing and eye movements. This model makes progress toward the goal of eliminating linking assumptions between memory constructs and empirical measures in favor of explicit theories of the coordinated control of motor responses and parsing.