Discussions of the relationship between perception and cognition often proceed without a definition of these terms. The sensory-modality specific nature of low-level perceptual processes provides a means of distinguishing them from cognitive processes. A more explicit definition of terms provides insight into the nature of the evidence that can resolve questions about the relationship between perception and cognition.

Correction of sensory transmission delays is an intractable problem, since there is no absolute reference for calibration. Phase-alignment is a practical alternative solution and can be realized by adaptive filters that operate locally with simple error signals.

In the target article, Cramer et al. suggest that diagnostic classification is improved by modeling the relationship between manifest variables (i.e., symptoms) rather than modeling unobservable latent variables (i.e., diagnostic categories such as Generalized Anxiety Disorder). This commentary discusses whether symptoms represent manifest or latent variables and the implications of this distinction for diagnosis and treatment.

Currently there is considerable interest in the notion that dorsal and ventral visual systems might differ in their specializations for thought and action. Behavior invariably involves multiple processes such as perception, judgment, and response execution. It is not clear that characteristics of the dorsal and ventral processing streams, as described by Norman, are entirely of a perceptual nature.