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  • Xpost from Scrib-L

    Dear Biomch-L readers,

    One of our long-standing subscribers posted the item below onto his own
    list this morning; I think that it might also be of interest to Biomch-L.

    Enjoy -- hjw.


    Date: Wed, 9 Sep 92 11:29:00 MET
    From: "Hans-Leo Teulings Tel:+31-80-615476 Fax:-615938"
    Subject: Invariant properties between stroke features
    "SCRIB-L Handwriting Production, Recognition, Reading, Education, Expertise"

    Dear Scrib-lers,

    The following paper can be retrieved by anonymous ftp (or requested by
    e-mail from the authors). Feel free to report troubles to


    cd pub/nici/handwriting/teulinvar
    mget *

    |Accepted: Acta Psychologica, 82, 1993. |
    |Submitted: 26 June 1992 |
    |Presented: 5th Handwriting Conference: Motor Control of Handwriting,|
    | October 27-30, 1991, Tempe, AZ, USA. |
    |Title: Invariant properties of handwriting motor programs to be |
    | employed in automatic handwriting recognition. |

    Invariant properties between stroke features in handwriting

    Hans-Leo Teulings & Lambert R.B. Schomaker

    Nijmegen Institute for Cognition and Information (NICI) University of
    Nijmegen, P.O.Box 9104, 6500 HE Nijmegen, The Netherlands E-mail: &, Fax: +31-80-615938


    A handwriting pattern is considered as a sequence of ballistic
    strokes. Replications of a pattern may be generated from a single,
    higher-level memory representation, acting as a motor program.
    Therefore, those stroke features which show the most invariant pattern
    are probably related to the parameters of the higher-level
    representation, whereas the more noisy features are probably related
    to the parameters derived at the lower levels (top-down hierarchy).
    This hierarchy of invariances can be revealed by the signal-to-noise
    ratio (SNR), the between-parameter correlations, and the
    between-condition correlations. Similarly, at the higher level a
    sequence of strokes may act as a unit from which individual strokes
    are derived (sequence hierarchy). This hierarchy of invariances can be
    revealed by the between-stroke correlation, which forms a weaker
    criterion than rescalability, which has been rejected mostly. Previous
    research showed that vertical stroke size has higher SNRs and higher
    between-condition correlations than stroke duration or peak force,
    whereas the latter two features were also negatively correlated. This
    suggested that vertical stroke size is a higher-level parameter than
    the other two. The present research largely confirmed this
    top-down-hierarchy and even for upstrokes and downstrokes separately.
    Downstrokes were more invariant than upstrokes in terms of vertical
    stroke size. However, contrary to the vertical stroke size, the
    horizontal stroke size was not invariant. Both vertical and horizontal
    sizes showed substantial between-stroke correlations. In contrast, the
    stroke durations did not show any between-stroke correlations. This
    suggests that stroke segmentation is reliable in spite of the discrete
    sampling of the handwriting movements.