Visual Scanning Behavior Research Articles

Behavioral assessment of psychiatric inpatients and normal controls across different environmental contexts

Objectively defined, publicly observable behaviors were time sampled for hospitalized psychiatric patients and normal controls in three distinct environmental contexts: lunch time, free time, and gym time. The behaviors sampled included body activity, extremity activity, proximity, social interactions, participation, visual scanning, laughing/smiling, and idiosyncratic behavior. Patient behaviors were recorded during both a drug-free baseline period and a subsequent medication period. The data suggest that consistent and reliable differences between patients and normals in most behaviors can be observed and that environmental context is an important determinant of these differences. Results are discussed in terms of their implications for assessment procedures and treatment decisions.

Visual Gap Perception: Judgment Performance at Different Times and the Evaluation of Psychophysical Methods

The first part of this study investigated the visual gap judgment performance of twenty-four subjects (21–37 years old) in the laboratory. A scaled down (1:12) two-dimensional gap display (black on yellow background) representing the front silhouette of a car and a post placed on the right side of the car was viewed by the subjects from a distance of 46 inches (total viewing angle of display 17 degrees). The width of the car represented the standard stimulus and the horizontal adjustable distance between the car and the post (gap) represented the test stimulus. The subjects were required to make a forced choice judgment with respect to whether the test stimulus distance (gap) was larger or smaller than the standard stimulus distance (car width). The subjects were tested twice on the same day, once using the randomized classical psychophysical method and once using the Up and Down Transformed Response (U.D.T.R.) rule. The data from the randomized classical psychophysical method was analyzed using the probit and the Kärber method of analysis. The data from the U.D.T.R. method was analyzed using a modified Wetherill estimation procedure. The second part of this study investigated the visual gap judgment performance and eye scanning behavior of two subjects over two days (seven experiments per day). Horizontal eye movements were recorded with a Biometrics Eye Movement Monitor system. The third part of this study investigated the efficacies of two psychophysical methods: The randomized classical method and the sequential U.D.T.R. rule. The results from part one of this study were used to determine a psychometric perception curve of an “average” human being. A digital computer simulation model was built to represent a human being's gap judgment responses and the experimental gap judgment situation. Each method was simulated for the following parameters: the step size between the stimulus levels, the bias of the starting point, and the selected number of trials in an experiment.

Method for recording and analyzing visual fixations in the unrestrained monkey.

Adaptation of the Mackworth wide-angle reflection eye camera for the collection and analysis of visual scanning behavior in the relatively unrestrained rhesus monkey is described. Crucial changes involved the addition of local fibre optic cable incident light, training the animal to view from a port by rewarding short trials, and computer-assisted data analysis for data reduction.

An optimal control model of human response part II: Prediction of human performance in a complex task

An optimal-control model of the human operator is used to analyze a manual control task involving the control of longitudinal position of a hovering VTOL aircraft. Using parameters that are obtained largely from analysis of simple experiments, it is shown that the model can reproduce the essential characteristics of pilots performing the VTOL task as well as system performance scores. In addition, the same optimization framework is used to predict visual scanning behavior.