This paper presents X-PRT, a new cognitive modeling tool supporting activities ranging from interface design to basic cognitive research. X-PRT provides a graphical model development environment for the CORE constraint-based cognitive modeling engine [7,13,21]. X-PRT comprises a novel feature set: (a) it supports the automatic generation of predictive models at multiple skill levels from a single taskspecification, (b) it supports a comprehensive set of modeling activities, and (c) it supports compositional reuse of existing cognitive/perceptual/motor skills by transforming high-level, hierarchical task descriptions into detailed performance predictions. Task hierarchies play a central role in X-PRT, serving as the organizing construct for task knowledge, the locus for compositionality, and the cognitive structures over which the learning theory is predicated. Empirical evidence supports the role of task hierarchies in routine skill acquisition. Author Keywords user modeling, tools for usability evaluation.

We describe concepts to support the analysis of cell phone menu hierarchies, based on cognitive models of users and easy-to-use optimization techniques. We present an empirical study of user performance on five simple tasks of menu traversal on an example cell phone. Two of the models applied to these tasks, based on GOMS and ACT-R, give good predictions of behavior. We use the empirically supported models to create an effective evaluation and improvement process for menu hierarchies. Our work makes three main contributions: a novel and timely study of a new, very common HCI task; new versions of existing models for accurately predicting performance; and a search procedure to generate menu hierarchies that reduce traversal time, in simulation studies, by about a third.

As driver distraction from in-vehicle devices becomes an increasingly critical issue, researchers have aimed to establish better scientific understanding of distraction along with better engineering tools to build less distracting devices. This paper presents a new system, Distract-R, that allows designers to rapidly prototype and evaluate new in-vehicle interfaces. The core engine of the system relies on a rigorous cognitive model of driver behavior which, when integrated with models of task behavior on the prototyped interfaces, generate predictions of driver performance and distraction. Distract-R allows a designer to prototype basic interfaces, demonstrate possible tasks on these interfaces, specify relevant driver characteristics and driving scenarios, and finally simulate, visualize, and analyze the resulting behavior as generated by the cognitive model. The paper includes three modeling studies that demonstrate the system’s ability to account for various aspects of driver performance for several types of in-vehicle interfaces. More generally, Distract-R illustrates how cognitive models can be used as internal simulation engines for design tools intended for non-modelers, with the ultimate goal of helping to understand and predict user behavior in multitasking environments. Categories and Subject Descriptors: H.1.2 [Models and Principles] User/Machine Systems – Human factors;

It has been well established in Cognitive Psychology that humans are able to strategically adapt performance, even highly skilled performance, to meet explicit task goals such as being accurate (rather than fast). This paper describes a new capability for generating multiple human performance predictions from a single task specification as a function of different performance objective functions. As a demonstration of this capability, the Cognitive Constraint Modeling approach was used to develop models for several tasks across two interfaces from the aviation domain. Performance objectives are explicitly declared as part of the model, and the CORE (Constraint-based Optimal Reasoning Engine) architecture itself formally derives the detailed strategies that are maximally adapted to these objectives. The models are analyzed for emergent strategic variation, comparing those optimized for task time with those optimized for working memory load. The approach has potential application in user interface and procedure design.

Portable music players such as Apple’s iPod have become ubiquitous in many environments, but one environment in particular has elicited new safety concerns and challenges — in-vehicle use while driving. We present the first study of portable music-player interaction while driving, examining the effects of iPod interaction by drivers navigating a typical roadway in a driving simulator. Results showed that selecting media on the iPod had a significant effect on driver performance as measured by lateral deviation from lane center; the effect was comparable to previously reported effects of dialing a cellular phone. In addition, selecting media and watching videos had a significant effect on carfollowing speed, resulting in speed reductions that presumably compensated for impaired lateral performance. Given that iPod interaction has become increasingly common while driving, these results serve as a first step toward understanding the potential effects of portable musicplayer interaction on driver behavior and performance. Author Keywords Driving, iPod, driver distraction, mobile computing.

This paper aims to provide a discussion of how model-based approaches and related tools have been used to address important issues for obtaining usable interactive software and the new challenges for this research area. The paper provides an analysis of the logical descriptions that can be used in the design of interactive systems and how they can be manipulated in order to obtain useful results. This type of approach has recently raised further interest in the ubiquitous computing field for supporting the design of multi-device interfaces. The new challenges currently considered are mainly in the area of end-user development, ambient intelligence, and multimodal interfaces.

The integration of cognitive models offers interesting theoretical and practical benefits to the development of complex models, but at the same time brings up new challenges that the modeling community is only beginning to address. In this paper we present our experiences integrating models and tools for modeling,. Specifically, on the modeling end, we integrated an ACT-R model of driving with an independently-built model of cell phone dialing. To do this, we integrated the driving tool (a minimal-graphics driving simulator that can be controlled by ACT-R) with a modelingby-demonstration tool, CogTool, that also used ACT-R as its cognitive engine. We found that both the models and tools required re-working because of the integration. The models required new motor movements and methods for switching between tasks. The tools required new specification techniques for placing prototyped devices in the vehicle and demonstration techniques for indicating points of taskswitching. Our experiences indicate that while the integration of cognitive models is indeed an approach worthy of pursuit, the field may not understand all the ramifications of such integration until many more integrated models and tools are developed.

Visual search is an important part of human-computer interaction. It is critical that we build theory about how people visually search displays in order to better support the users ’ visual capabilities and limitations in everyday tasks. One way of building such theory is through computational cognitive modeling. The ultimate promise for cognitive modeling in HCI it to provide the science base needed for predictive interface analysis tools. This paper discusses computational cognitive modeling of the perceptual, strategic, and oculomotor processes people used in a visual search task. This work refines and rounds out previously reported cognitive modeling and eye tracking analysis. A revised “minimal model ” of visual search is presented that explains a variety of eye movement data better than the original model. The revised model uses a parsimonious strategy that is not tied to a particular visual structure or feature beyond the location of objects. Three characteristics of the minimal strategy are discussed in detail. Author Keywords Visual search, cognitive modeling, cognitive strategies, eye

Visual search is an important part of human-computer interaction (HCI). The visual search processes that people use have a substantial effect on the time expended and likelihood of finding the information they seek. This dissertation investigates visual search through experiments and computational cognitive modeling. Computational cognitive modeling is a powerful methodology that uses computer simulation to capture, assert, record, and replay plausible sets of interactions among the many human processes at work during visual search. This dissertation aims to provide a cognitive model of visual search that can be utilized by predictive interface analysis tools and to do so in a manner consistent with a comprehensive theory of human visual processing, namely active vision. The model accounts for the four questions of active vision, the answers to which are important to both practitioners and researchers in HCI: What can be perceived in

Motivation – To create a cognitive simulation model that predicts text entry performance and learning on cell phone keypads by novice users. Research approach – A programmable cognitive architecture, ACT-R, is used to execute the simulation model. Part of the simulation result is compared with the result of a previous user study. Findings/Design – The proposed model is an a priori model (not tuned to any real user data) that predicts the amount of time spent in finding a key on the keypad and pressing it repeatedly. The predicted amount of time in finding a key differs by 6 % and the time between two repeated key-presses of the same key by 27 % compared to the results of a previous user study. The model also captures the learning of keypad layout by novice users. Memorization of keypad layout is simulated using task repetition. Research limitations/Implications – This research has several limitations described towards the end of this paper. An important one among them is that the work does not model the impact of visual distracters in the field of view (frontal surface of the handset) on user performance. Originality/Value – This is the first cognitive simulation model of novice user’s text entry performance and learning on cell phone keypads. Take away message – This work introduces an a priori cognitive model of text entry by novice users. This forms a basis for systematic exploration of keypad designs for cell phones in shorter time and lower cost.