[Overview] [Goals and Assessment] [Readings] [Software] [Syllabus: 1 2 3 4 5]

85-419/719: Introduction to Parallel Distributed Processing

Spring 2012, Tue/Thu 10:30-11:50am, Porter A19

Instructor: David Plaut
Baker 254N, x85145
plaut@cmu.edu

Course webpage: http://www.cnbc.cmu.edu/~plaut/IntroPDP/

Announcements

[Feb 1] There is a new version of Lens-OSX.zip for Mac OS X in which the problem is fixed. Fixed versions for Windows and Linux will be available shortly.
[Jan 24] Lens will crash (segfault) on a left-click to a unit in the Unit Display anytime after the palette has been changed. This is true on every platform (Linux, Windows, Mac OS X). The good news is that there's no real reason to left-click on a unit, so try not to (right-clicking to display weights is fine). I'll try to track this down and fix it if possible.

Assignments

Homework 1 (feedback)
Homework 2 (due Tue Feb 14)

Overview

The goal of the course is to introduce the basic principles of parallel distributed processing (also known as connectionist or neural network modeling) and to illustrate how these principles provide insight into human cognitive processing. In addition, the course will cover some issues in neural and cognitive development, cognitive impairments due to brain damage, and some basic computational issues. The course also attempts to introduce the general practice of studying cognition through computational modeling and analysis. There will be computer simulation exercises in addition to readings. Homework assignments will generally require you to report the results of simulations you have carried out, to analyze these results, and to think critically about some issues raised in the readings. There will also be a final project that will typically involve simulation modeling.

The course is divided into five sections. The first three cover basic topics in parallel distributed processing. For each of these, a homework assignment is handed out at the beginning of the section and is due at the end of the section. At the end of the third section, you will also be required to submit a one-page proposal outlining the final project you intend to carry out. This will be returned with feedback at the beginning of the fourth section (right after Spring Break), and you will be expected to get started on your project immediately thereafter. You should be on the lookout throughout the earlier sections of the course for topics or issues that you find particularly interesting and would like to pursue in more detail in a project. The fourth section focuses on applications from a range of perceptual, linguistic and cognitive domains, and will be followed by a take-home essay based on class lectures and readings. The final section will be devoted to brief oral reports from each student on the topic of their project. A 12-15 page final paper based on the project is due at the end of this last section. There is no final exam for the course.

In general, there are assigned readings for each lecture that are intended to prepare you to participate in the class discussion for that day. In addition, there may be optional background readings (marked with "opt:" in the Syllabus) that serve either as the basis for the lecture, to present an alternative point of view, or simply to make available to you relevant material that we won't have time to cover in class. Optional readings are also a good source of ideas for projects. There are no required readings on days when something is due, but you are still expected to attend class, hand in your homework, and draw on the material you have already learned in order to participate in the discussion.

Course Goals and Assessment

Below are the broad goals of the course and how each is assessed (listed in brackets).

Extend breadth of knowledge of cognitive psychology, including theoretical perspectives, research findings, and applications [through assigned readings, homeworks, and in-class discussions]
Foster familiarity with diverse experimental paradigms used in psychology [through hands-on experience with computational modeling, assessed via homework assignments and the final project].
Engender the ability to read and critique psychological articles [assessed through homework assignments, take-home exam, and in-class discussions of assigned readings].
Improve skill in oral and written presentation [through the oral project presentation and written final project report].
Increase facility in designing psychological studies to address research questions [through the design of a final modeling project].
Foster critical thinking and creativity [through in-class discussions and the formulation and execution of a final project].

The grading in the class will be divided up as follows:

Homework 1:	10%
Homework 2:	15%
Homework 3:	20%
Project proposal:	5%
Take-home essay:	15%
Oral presentation/class participation:	5%
Final project	30%

Assignments should be handed in as physical print-outs and are due at the beginning of class on the date listed in the Syllabus (usually a Tuesday). Late penalties will be assessed as follows: Homeworks handed in late but before 5pm of the next day (usually a Wednesday) will be penalized by 5% of the total possible points; those handed in before 5pm of the following weekday (usually a Thursday, but a Monday if the homework was due on a Thursday) will be penalized by 10%; those handed in later than that but before graded papers are returned will be penalized by 15%. Papers may not be handed in for credit after other students' graded homeworks are returned and feedback is posted to the course webpage, unless you get explicit permission from the instructor. Late homeworks may be submitted to the instructor by email (pdf file). The 5% for class participation will be based on contributions to class discussions throughout the semester, and on the quality of the oral project report.

Readings

There is no required text for the course. All assigned and optional readings are available as downloadable pdf files from links in the Syllabus below. Other course materials (e.g., handouts, assignments, etc.) will be made available via links at the top of this web page.

The following texts contain some of the course readings and may be useful as general references:

PDP1: Rumelhart, D. E., McClelland, J. L., & the PDP research group (1986). Parallel distributed processing: Explorations in the microstructure of cognition. Volume 1: Foundations. Cambridge, MA: MIT Press.
PDP2: McClelland, J. L., Rumelhart, D. E., & the PDP research group (1986). Parallel distributed processing: Explorations in the microstructure of cognition. Volume 2: Psychological and biological models. Cambridge, MA: MIT Press.
PDP Handbook: McClelland, J. L. and Rumelhart, D. E. (1988). Explorations in parallel distributed processing: A handbook of models, programs, and exercises. Cambridge, MA: MIT Press.
MPR: McLeod, P., Plunkett, K. and Rolls, E. T. (1998). Introduction to Connectionist Modelling of Cognitive Processes. Oxford: Oxford University Press.

Software

We will be using a software package called "Lens" (for Light Efficient Network Simulator), developed by former CMU CS graduate student Doug Rohde. Lens runs under Windows, Mac OSX, and Linux. The main website for Lens is http://tedlab.mit.edu/~dr/Lens/. You can download a file containing a precompiled version of Lens here:

Windows
Download the file Lens-windows.zip and use WinZip or a similar program to unzip the file. Inside the resulting folder will be a folder called "Lens". Read the file "README.rtf" in this directory for further instructions. Because of differences in the way Windows and Unix-based systems handled spaces, it will simply things if you put the Lens directory at the top level of the drive (i.e., C:\Lens).
Mac OS X
Download the file Lens-OSX.zip and double-click it to create an unzipped version. Inside will be a folder called "Lens". Read the text file README.txt in this folder for further instructions.
Linux
Download the file Lens-linux.tar.gz. Open a terminal and untar it with the command "tar xzf Lens-linux.tar.gz". This will create a directory called "Lens". Read the text file README in this directory for further instructions.

If you have any problems getting Lens running, contact the instructor. After installing Lens, you should look at the online manual at http://tedlab.mit.edu/~dr/Lens/, particular the instructions under "Running Lens" and the Tutorial Network under "Example Networks". The precompiled versions of Lens come with a offline (local) copy of the manual that can be accessed by pointing your web browser at Manual/index.html in the Lens directory.

Syllabus

This syllabus is subject to change throughout the course, so be sure to revisit this web page frequently.

Section 1: Processing and Constraint Satisfaction

Jan 17 (Tue): Overview and basic principles (slides)
[HOMEWORK 1 POSTED] [Install Lens (see Software section)]

Rumelhart, D. E. (1989). The architecture of mind: A connectionist approach. In M. I. Posner (Ed.), Foundations of cognitive science (pp. 133-159). Cambridge, MA: MIT Press.

Jan 19 (Thu): Lens tutorial

Jan 24 (Tue): Constraint satisfaction

McLeod, P., Plunkett, K. and Rolls, E. T. (1998). The attraction of parallel distributed processing for modelling cognition. MPR, Chapter 2.

Jan 26 (Thu): Schema theory

Rumelhart, D. E., Smolensky, P., McClelland, J. L., & Hinton, G. E. (1986). Schemata and sequential thought processes in PDP models. PDP2, Chapter 14.

Jan 31 (Tue): Psychological implications (slides)
[HOMEWORK 1 DUE]

(opt: McClelland, J. L. & Rumelhart, D. E. (1981). An interactive activation model of context effects in letter perception: Part 1. An account of basic findings. Psychological Review, 88, 375-407.)
(opt: McClelland, J. L. & Elman, J. L. (1986). The TRACE model of speech perception. PDP2, Chapter 15.)
(opt: Dell, G. S., Schwartz, M. F., Martin, N., Saffran, E. M., & Gagnon, D. A. (1997). Lexical access in normal and aphasic speakers. Psychological Review, 104, 801-838.)

Section 2: Simple Learning and Distributed Representations

Feb 2 (Thu): Hebb and Delta rules (slides)
[HOMEWORK 2 POSTED]

McClelland, J. L., and Rumelhart, D. E. (1988). The pattern associator. PDP Handbook, Chapter 4 (pp. 83-96).
(opt: McLeod, P., Plunkett, K. and Rolls, E. T. (1998). Pattern association. MPR, Chapter 3.)

Feb 7 (Tue): Hebb and Delta rules (continued)

Feb 9 (Thu): Distributed representations (slides)

Hinton, G. E., McClelland, J. L., & Rumelhart, D. E. (1986). Distributed representations. PDP1, Chapter 3.
(opt: Plaut, D. C. and McClelland, J. L. (2010). Locating object knowledge in the brain: A critique of Bowers's (2009) attempt to revive the grandmother cell hypothesis. Psychological Review, 117, 284-290.)

Feb 14 (Tue): Psychological implications (slides)
[HOMEWORK 2 DUE]

McClelland, J. L. & Rumelhart, D. E. (1985). Distributed memory and the representation of general and specific information. Journal of Experimental Psychology: General, 114, 159-188.
(opt: McLeod, P., Plunkett, K. and Rolls, E. T. (1998). Autoassociation. MPR, Chapter 4.)

Section 3: Learning Internal Representations

Feb 16 (Thu): Back-propagation (slides)
[HOMEWORK 3 POSTED]

Rumelhart, D. E., Hinton, G. E., & Williams, R. J. (1986). Learning internal representations by error propagation. PDP1, Chapter 8.
(opt: Hinton, G. E. (1989). Connectionist learning procedures. Artificial Intelligence, 40, 185-234.)

Feb 21 (Tue): Temporal learning and recurrent networks (slides)

Elman, J. L. (1990). Finding structure in time. Cognitive Science, 14, 179-211.
(opt: Williams, R. J. & Zipser, D. (1995). Gradient-based learning algorithms for recurrent networks and their computational complexity. In Y. Chauvin & D. E. Rumelhart (Eds.), Back-propagation: Theory, architectures, and applications (pp. 433-486). Hillsdale, NJ: Erlbaum.)

Feb 23 (Thu): Generalization and overfitting (slides)

(opt: Morgan, N. & Bourlard, H. (1990). Generalization and parameter estimation in feedforward nets: Some experiments. In D. S. Touretzky (Ed.), Advances in neural information processing systems 2. San Mateo: CA: Morgan Kaufmann, 630-637. )
(opt: le Cun, Y., Denker, J. S., & Solla, S. A. (1990). Optimal brain damage. In D. S. Touretzky (Ed.), Advances in neural information processing systems 2. San Mateo: CA: Morgan Kaufmann, 598-605.)
(opt: Weigand, A. S., Rumelhart, D. E., & Huberman, B. A. (1991). Generalization by weight-elimination with application to forcasting. In R. P. Lippmann, J. E. Moody, & D. S. Touretzky (Eds.), Advances in neural information processing systems 3. San Mateo: CA: Morgan Kaufmann, 875-882.)

Feb 28 (Tue): Contrastive Hebbian learning (slides)

Hinton, G. E. & Sejnowski, T. J. (1986). Learning and relearning in Boltzmann Machines. PDP1, Chapter 7.

Mar 1 (Thu): Unsupervised learning (slides)

Rumelhart, D. E. & Zipser, D. (1986). Feature discovery by competitive learning. PDP1, Chapter 5.
(opt: Kohonen, T. (1990). The self-organizing map. Proceedings of the IEEE, 78, 1465-1480.)

Mar 6 (Tue): Reinforcement learning (slides)

Barto, A. G. (1995). Reinforcement learning; Reinforcement learning in motor control. In M. A. Arbib (Ed.), The handbook of brain theory and neural networks (pp. 804-813). Cambridge, MA: MIT Press.
(opt: Tesauro, G. (1995). Temporal difference learning and TD-Gammon. Communications of the ACM, 38, 58-68.)

Mar 8 (Thu): Psychological implications
[PROJECT PROPOSAL DUE] [HOMEWORK 3 DUE]

(opt: McClelland, J. L. (2001). Failures to learn and their remediation: A Hebbian account. In J. L. McClelland and R. S. Siegler (Eds.), Mechanisms of cognitive development: Behavioral and neural perspectives, (pp. 97-121). Mahwah, NJ: Lawrence Erlbaum Associates.)
(opt: McCandliss, B. D., Fiez, J. A., Protoapas, A., Conway, M., McClelland, J. L. (2001). Success and failure in teaching the [r] [l] contrast to Japanese adults: Tests of a Hebbian model of plasticity and stabilization in spoken language perception. Cognitive, Affective, & Behavioral Neuroscience, 2, 89-108.)

Mar 13 (Tue): NO CLASS (Spring Break)

Mar 15 (Thu): NO CLASS (Spring Break)

Section 4: Applications

Mar 20 (Tue): Cognitive development (slides)

Munakata, Y. and McClelland, J. L. (2003). Connectionist models of development. Developmental Science, 6, 413-429.
(opt: Munakata, Y., McClelland, J. L., Johnson, M. H. & Siegler, R. (1997). Rethinking infant knowledge: Toward an adaptive process account of successes and failures in object permanence tasks. Psychological Review, 104, 686-713.)

Mar 22 (Thu): Memory and the hippocampus (slides)

McClelland, J. L., McNaughton, B. L., and O'Reilly, R. C. (1995). Why there are complementary learning systems in the hippocampus and neocortex: Insights from the successes and failures of connectionist models of learning and memory. Psychological Review, 102, 419-457.

Mar 27 (Tue): High-level vision and attention [lecture by M. Behrmann] (slides: vision) (slides: faces and words)

Mozer, M. C. and Sitton, M. (1998). Computational modeling of spatial attention. In H. Pashler (Ed.), Attention (pp. 341-393). Hove, England: Psychology Press/Erlbaum.
(opt: Mozer, M. C. and Behrmann, M. (1990). On the interaction of selective attention and lexical knowledge: A connectionist account of neglect dyslexia. Journal of Cognitive Neuroscience, 2, 96-123.)
(opt: Behrmann, M., Zemel, R. S. and Mozer, M. C. (1998). Object-based attention and occlusion: Evidence from normal participants and a computational model. Journal of Experimental Psychology: Human Perception and Performance, 24, 1101-1036.)
(opt: Plaut, D. C. and Behrmann, M. (2011). Complementary neural representations for faces and words: A computational exploration. Cognitive Neuropsychology, 28, 251-275.)

Mar 29 (Thu): Language: Morphology (slides)

The past-tense debate. Trends in Cognitive Sciences, 2002, 6, 456-474. [Pinker, S. & Ullman, M T. The past and future of the past tense, 456-463; McClelland, J. M. & Patterson, K. 'Words or Rules' cannot exploit the regularity in exceptions: Reply to Pinker and Ullman, 464-465; McClelland, J. M. & Patterson, K. Rules or connections in past-tense inflections: What does the evidence rule out?, 465-472; Pinker, S. & Ullman, M T. Combination and structure, not gradedness, is the issue: Reply to McClelland and Patterson, 472-474.]
(opt: Rumelhart, D. E. & McClelland, J. L. (1986). On learning the past tenses of English verbs. PDP2, Chapter 18.)

Apr 3 (Tue): Language: Word reading (slides)

Plaut, D. C. (1999). Computational modeling of word reading, acquired dyslexia, and remediation. In R. Klein and P. A. McMullen (Eds.), Converging methods in reading and dyslexia (pp. 339-372). Cambridge, MA: MIT Press.
(opt: Plaut, D. C., McClelland, J. L., Seidenberg, M. S., & Patterson, K. (1996). Understanding normal and impaired word reading: Computational principles in quasi-regular domains. Psychological Review, 103, 56-115.)
(opt: Coltheart, M., Rastle, K., Perry, C. and Langdon, R. & Ziegler, J. (2001). DRC: A dual route cascaded model of visual word recognition and reading aloud. Psychological Review, 108, 204-256.)

Apr 5 (Thu): Language: Sentence processing (slides)

McClelland, J. L., St. John, M., & Taraban, R. (1989). Sentence comprehension: A parallel distributed processing approach. Language and Cognitive Processes, 4, 287-335.
(opt: Elman, J. L. (1993). Learning and development in neural networks: The importance of starting small. Cognition, 48, 71-99.)
(opt: Rohde, D. L. T., and Plaut, D. C. (1999). Language acquisition in the absence of explicit negative evidence: How important is starting small? Cognition, 72, 67-109.)
(opt: Frazier, L. (1987). Sentence processing: A tutorial review. In M. Coltheart (Ed.), Attention and performance XII: The psychology of reading (pp. 559-586). Hillsdale, NJ: Erlbaum.)

Apr 10 (Tue): Semantics [lecture by B. Armstrong] (slides)

McClelland, J. L. and Rogers, T. T. (2003). The parallel distributed processing approach to semantic cognition. Nature Neuroscience Reviews, 4, 310-322.
(opt: Plaut, D. C. (2002). Graded modality-specific specialization in semantics: A computational account of optic aphasia. Cognitive Neuropsychology, 19, 603-639.)
(opt: Farah, M. J. and McClelland, J. L. (1991). A computational model of semantic memory impairment: Modality specificity and emergent category specificity. Journal of Experimental Psychology: General, 120, 339-357.)

Apr 12 (Thu): Routine action (slides)
[TAKE-HOME ESSAY POSTED (covering Mar 20 to Apr 12)]

Botvinick, M. and Plaut, D. C. (2004). Doing without schema hierarchies: A recurrent connectionist approach to normal and impaired routine sequential action. Psychological Review, 111, 395-429.
(opt: Cooper, R. P., and Shallice, T. (2006). Hierarchical schemas and goals in the control of sequential behavior. Psychological Review, 113, 887-916.)
(opt: Botvinick, M., and Plaut, D. C. (2006). Such stuff as habits are made on: A reply to Cooper and Shallice (2006). Psychological Review, 113, 917-928.)
(opt: Cooper, R. P., and Shallice, T. (2006). Structured representations in the control of behavior cannot be so easily dismissed: A reply to Botvinick and Plaut (2006), 929-931.)

Apr 17 (Tue): Cognitive control and executive function
[TAKE-HOME ESSAY DUE]

(opt: Rumelhart, D. E., Smolensky, P., McClelland, J. L., & Hinton, G. E. (1986). Schemata and sequential thought processes in PDP models. PDP2, Chapter 14, pages 38-57.)
(opt: Cohen, J. D., Aston-Jones, G., and Gilzenrat, M. S. (2004). A system-level perspective on attention and cognitive control: Guided activation, adaptive gating, conflict monitoring, and exploitation versus exploration. In M. I. Posner (Ed.), Cognitive Neuroscience of Attention (pp. 71-90). New York: Guilford Press.)

Apr 19 (Thu): NO CLASS (Spring Carnival)

Section 5: Project Progress Reports

Apr 24 (Tue):
Apr 26 (Thu):
May 1 (Tue):
May 3 (Thu):
May 4 (Fri) 5pm: FINAL PROJECT PAPER DUE