Figure 7.

The adverse effect that a bright screen reflection can have on thresholds. The panel on the left was obtained when the observer was tested in a darkened room: it shows the decibel values with a normal MD (0.14) and PD (2.9). The panel on the right shows the result for the same observer (dB values and gray scale inset) when tested with the reflection of a bright window visible in the right upper half of the screen. Here the mean defect (MD) was −2.48 and pattern defect (PD) 5.82. Note, the test pattern is a subset of the full 66-point grid that takes approximately 3 minutes for completion.