[visionlist] Teller Acuity Cards

[Christopher Taylor]

Why do you believe this test has a fundamental error versus TAC testing? It
is a different test, no more, no less.

To play devil's advocate, one could claim that Teller Acuity Cards lack
ecological validity because they do not present contours and objects, which
are more important to the visual system during daily living than sinusoidal
or square-wave gratings.  That said performance on this test and TAC ought
to correlate and if this new test has other benefits (e.g, faster/easier to
administer, cheaper and more available to purchase, and so on...) and has
appropriate age-norms for the population being screened then might it not
be an advance on traditional TAC testing?

Best,

C

On Thu, Feb 13, 2020 at 9:36 AM Meindert de Vries <meindertdevries at visio.org>
wrote:

> Dear members ,
>
>
>
> Since 1992 I work for Visio, an institution the helps visually impaired
> people. We have always been using the Teller Acuity Cards to determine
> the visual acuity in children.
>
> A new test has been presented on the scene, proposing to replace the
> Teller Acuity cards, because the TAC are expensive and sometime difficult
> to get. I enclose an example picture of the new cards.
>
>
>
> From my perspective and knowledge they have made some fundamental errors
>
> 1.       The test seems  ambiguous to me, because both object recognition
> part of our visual system as well as the much ‘lower” detection part of our
> visual system is triggered by this stimulus
>
> 2.       The spatial frequency content of these stimuli (checkerboard
> patterns with a distinctive contour) is in the Fourier domain essentially
> different from the TAC bar patterns without a contour; nevertheless the
>  same cycl/cm are used.
>
> 3.       In addition to point 2: I think that the contour is a much
> stronger stimulus than the checkerboards.
>
>
>
> Could anybody reflect on this ?
>
>
>
> Most kindley,
>
>
>
>
>
> *drs. M.J. de Vries 69024716001*
>
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