Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /var/www/arngren.com/phd.arngren.com/phd/index.php:11) in /var/www/arngren.com/phd.arngren.com/phd/libraries/joomla/session/session.php on line 423

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /var/www/arngren.com/phd.arngren.com/phd/index.php:11) in /var/www/arngren.com/phd.arngren.com/phd/libraries/joomla/session/session.php on line 423

Warning: Cannot modify header information - headers already sent by (output started at /var/www/arngren.com/phd.arngren.com/phd/index.php:11) in /var/www/arngren.com/phd.arngren.com/phd/libraries/joomla/session/session.php on line 426
Modelling Cognitive Representations

Modelling Cognitive Representations

Morten Arngren

Abstract: This thesis analyzes the modelling of visual cognitive representations based on extracting cognitive components from the MNIST dataset of handwritten digits using simple unsupervised linear and non-linear matrix factorizations both non-negative and unconstrained based on gradient descent learning.

We introduce two different classes of generative models for modelling the cognitive data: Mixture Models and Deep Network Models. Mixture models based on K-Means, Guassian and factor analyzer kernel functions are presented as simple generative models in a general framework. From simulations we analyze the generative properties of these models and show how they render insufficient to proper model the complex distribution of the visual cognitive data.

Motivated by the introduction of deep belief nets by Hinton et al. [12] we propose a simpler generative deep network model based on cognitive components. A theoretical framework is presented as individual modules for building a generative hierarchical network model.

We analyze the performance in terms of classification and generation of MNIST digits and show how our simplifications compared to Hinton et al. [12] leads to degraded performance. In this respect we outline the differences and conjecture obvious improvements.

Morten Arngren,
Modelling Cognitive Representations, Master Thesis, DTU 2007

  author = {Morten Arngren},
  title = {Modelling Cognitive Representations},
  school = {DTU Informatics, Intelligent Signal Processing},
  year = {2007},
  month = {April},