[ CogSci Summaries home | UP | email ]

Gary McGraw, John Rehling & Robert Goldstone. (1994) Letter Perception: Toward a conceptual approach. In the Proceedings of the Sixteenth Annual Conference of the Cognitive Science Society, pages 613-618, Atlanta, GA, August 1994.

Author of the summary: Patrawadee Prasangsit, 1999, pp@cc.gatech.edu

The actual paper is online.

Cite this paper for:


This paper shows that roles play an important part in letter perception.  It presents the results of a simple experiment in lowercase letter recognition.

The concept, for instance, lowercase-'a' can be thought of as a component composed of two smaller ideas: (1) the idea of a curved umbrella-handle-like bar on the right, and (2) the idea of a small c-like curve on the left.  These two conceptual components, which are called roles, are not explicit shapes per se but are ideas about what the acceptable bounds for letter-part shapes are, how far such shapes can be stretched before they lose their interpretation, and how they interact with other roles to form a complete object.  Roles and relationships between roles make up the internal structure of a letter category.  Category membership at the whole-letter level is determined by category membership at the lower level of roles.

Slippage involves allowing certain descriptions in a mental representation to "slip, " or be replaced by related descriptions according to contextual pressures brought to bear by the situation.

Each letter is formed by a set of short line segments, called quanta, on a fixed grid of dimension 3x7.  See figure 3.

Subjects are presented with a number of lowercase letters, one at a time, both in normal and styled shapes (called NORMALS and FONTS, respectively), and asked to identify them.  Based on the results, the authors make some predictions:

Prediction 1

Prediction 2 Prediction 3 Prediction 4 Conclusion: Results from the experiments provide evidence for the existence of conceptual-level representations of letter parts, namely roles.  The authors intend to incorporate such representations into a computer model of letter recognition.

Summary author's notes:

Back to the Cognitive Science Summaries homepage
Cognitive Science Summaries Webmaster:
JimDavies ( jim@jimdavies.org )

Last modified: Wed May 12 01:02:17 EDT 1999