Learning features while learning to classify: a cognitive model for autonomous systems

Abstract

We describe a computational cognitive model intended to be a generalizable classifier that can provide context-based feedback to semantic perception in robotic applications. Many classifiers (including cognitive models of categorization) perform well at the task of associating features with objects. Underlying their performance is an effective selection of the features used during classification. This feature selection (FS) process is usually performed outside the boundaries of the models that learn and perform classification tasks, often by human experts. In contrast, the cognitive model we describe simultaneously learns which features to use, as it learns the associations between features and classes. This integration of FS and class learning in one model makes it complementary to other machine-learning techniques that generate feature-based representations (e.g., deep learning methods). But their integration in a cognitive architecture also provides a means for creating a dynamic context that includes disparate sources of information (e.g., environmental observations, task knowledge, commands from humans). This richer context, in turn, provides a means for making semantic perception goal-directed. We demonstrate automated FS, integrated with an instance-based learning approach to classification, in an ACT-R model of categorization by labeling facial expressions of emotion (e.g., happy, sad), and then generalizing the model to the classification of indoor public spaces (e.g., cafes, classrooms).