Considering Subjective Factors in Performance Models for Human- Computer Interface Design and Evaluation
Jing Kong · Institutional Repositories DataBase (IRDB) · 2006
Considering Subjective Factors in Performance Models forHuman-Computer Interface Design and Evaluation Jing KongPointing tasks are basic and important for interaction in human-computer interfaces.A large numbers of candidate interfaces and devices for pointing tasks require reliable models for device evaluation and design guidance.Fitts' law is one of the most famous models for pointing task in HCI and has been used widely.Unfortunately, it is established on a thin theoretic base and its adequacy remains debatable.The subjective factors or the humans individual factors cannot be indicated reliably by Fitts' law.Moreover, the two existing forms of Fitts' law complicate the application situation.We regard that there are two layers of speedaccuracy tradeoffs affecting the pointing performance, the task layer and the subjective layer.Through a series of special manipulated experiments, we analyzed the two forms of Fitts' law from the aspect of reconciling the two layers of speed-accuracy tradeoffs.Our investigation reveals the nature and relationship of the two layers of speed-accuracy tradeoffs in pointing tasks.Moreover, the analysis gives a comprehensive comparison of the two forms of Fitts' law to clean away the doubts and hesitation existing in model selection all along.This work helps us to realize that it is impossible to model the two layers of speed-accuracy tradeoffs in pointing tasks by the simple relationship described in Fitts' law models accurately and completely.Then we established a new model for pointing tasks through analyzing the data of the performance time.We named the new model as SH-Model, which takes the human factors or, the subjective factors into consideration from the aspect of performance successful rates.A statistical tool, AIC, was applied for model evaluation.According to the AIC values, the SH-Model is better than the traditional models.Around the topic of subjective factors in modeling, we have also studied the optimal effective target width calculation method of Fitts' law.Using the data from the experiment where the subjects were instructed to perform with different speed-accuracy tradeoffs, we explored the information processing or transmission rate of the human motor system.The application research of evaluation models on colors effects on pointing tasks had also been studied.This work will contribute to considering the human or subjective factors in modelingAs in many human-performed tasks, the more precisely the task is to be accomplished, the slower it is.Conversely, the faster the task is completed, the less precisely the task tends to be performed.