This repository contains the homework assignments, project work, and supplementary materials for COGS 511 – Computational Models of Mind, Fall 2025. It focuses on the study and implementation of cognitive architectures, including ACT-R and Nengo, providing practical examples and exercises in modeling human cognition computationally. The repository includes code, simulation files, and documentation to support hands-on learning and exploration of cognitive modeling concepts.
Homework 1 implements ACT-R models of two-digit addition and subtraction, using structured chunks, goal-driven procedures, and finger counting to simulate carries and borrows while leveraging declarative memory and procedural rules to manage the task flow.
Homework 2 implements an ACT-R model of letter recognition and comparison, using goal-driven visual attention and imaginal encoding to sequentially attend to three letters, store them in memory, and determine which letter differs from the others. It runs with the unit2.lisp code located in ACT-R\tutorial\lisp.
Homework 3 implements an ACT-R model of alphabet–arithmetic verification (Zbrodoff-style) in which the model processes expressions of the form letter + number = letter. It sequentially attends to and encodes the first letter, the number, and the target letter using visual attention and subvocal rehearsal. The model then attempts to retrieve a stored solution from declarative memory. When retrieval fails, it computes the answer through a serial letter-counting process that increments both letters and numbers. Finally, the model compares the derived or retrieved result with the target letter and produces a yes/no motor response, thereby contrasting retrieval-based and algorithmic solution pathways within the architecture.