Feature Saliency in Artificial Neural Networks with Application to Modeling Workload

This dissertation research extends the current knowledge of feature saliency in artificial neural networks ANN. Feature saliency measures allow for the user to rank order the features based upon the saliency, or relative importance, of the features. Selecting a parsimonious set of salient input features is crucial to the success of any ANN model. In this research, several methodologies were developed using the Signal to Noise Ratio SNR Feature Screening Method and its associated SNR Saliency Measure for selecting a parsimonious set of salient features to classify pilot workload in addition to air traffic controller workload. Candidate features were derived from electroencephalography EEG, electrocardiography EKG, electro-oculography EOG, and respiratory gauges. In addition, a new saliency measure was developed that can account for time in Elman Recurrent Neural Networks RNN. This Partial Derivative Based Spatial Temporal Saliency Measure is used via a Spatial Temporal Feature Screening Method for selecting a parsimonious set of salient features in both time and space. Finally, a technique for investigating the memory capacity of an Elman RNN was developed.