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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Regarding the stream on the new “acuity” test figures shown by DeVries. Interesting comments!<o:p></o:p></p><p class=MsoNormal>Angie’s comments bring up the issue about whether a specific shape is perceived similarly at threshold vs. suprathreshld levels. But if this is a detection task, why does that matter? However, if the overall areas of the shapes differ which appears so from the photos, this should invalidate a presumption of equivalent detection at threshold. Also there is problem in using different shapes in that infants and children may have preferences for certain shapes, for example, those that they recognize. Answering Chris Taylor’s advocacy for a more ecologically valid stimulus than gratings, this is a good concern. However, the challenges of designing such a test that meets all the requirements for stimulus properties and consistency and validity seem daunting. Designing a test of form or shape discrimination appropriate for infants/children could have clinical utility for assessing risk of cerebral/cortical visual impairment. I can’t imagine, however, that the test designt could be done simply, using a preferential looking paradigm. Maybe, I’m wrong and there’s already such a test.<o:p></o:p></p><p class=MsoNormal>Also, isn’t it the case that spatial frequency power of a checkerboard is at the diagonal? Wonder if the designers calculated cy/cm using check width or the diagonal? <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>