The target article fails to disentangle the functional description from the structural description of the two somatosensory streams. Additional evidence and thorough reconsideration of the evidence cited argue for a functional distinction between the how processing and the what processing of somatosensory information, while questioning the validity and usefulness of the equation of these two types of processing with structural streams. We propose going one step further: to investigate how the distinct functional streams are coordinated via attention.

Humphreys and Forde conceptualize object representations as structural descriptions, without discussing the implications of structural description models. We argue that structural description models entail two major assumptions – a part-structure assumption and an invariance assumption. The invariance assumption is highly problematic because it contradicts a large body of findings which indicate that recognition performance depends on orientation and size. We will delineate relevant findings and outline an alternative conception.

Cowan defines a chunk as “a collection of concepts that have strong associations to one another and much weaker associations to other chunks currently in use.” This definition does not impose any constraints on the nature and number of elements that can be bound into a chunk. We present an experiment to demonstrate that such limitations exist for visual short-term memory, and that their analysis may lead to important insights into properties of visual memory.