The patient DF has predominately been studied in terms of a dissociation between relatively preserved vision for action, and a profound disruption to vision for perception. This talk will focus just on DF’s residual vision for perception, and highlight how this patient’s visual form-agnosia impairs the construction of surfaces and the ability to guide attention within objects. Indeed we will demonstrate that configural information that normally offers a huge advantage to healthy observers actually places a large cost on DF’s search performance. These studies offer some important insights into the underlying mechanisms responsible for constructing Gestalts. These insights are however significantly limited when restricted to the results of one patient, with a necessarily idiosyncratic lesion. For this reason we have developed the L-POST, or Leuven Perceptual Organization Screening Test, which consists of 15 sub-tests to assess a range of Gestalt and mid-level phenomena. The test is implemented online, is free to use, has a norming sample of over 1200, and has been validated with over 40 patients. The test allows clinicians to screen for deficits in visual perception, and enables researchers to get a broader overview of the Gestalt and mid-level processes that are preserved or disrupted in a given patient.