Abstract
Mental spatial transformations such as rotation and folding have been
well-characterised both behaviorally and electrophysiologically.
However, the parity of mental rotation and mental folding mechanisms is
an unresolved question. The neurophysiological signature of mental
rotation is a late negative deflection over parietal regions that
becomes more negative with greater rotation angles. The same negativity
is present during mental folding, but typically does not change in
amplitude with different folding difficulties. This dissociation
suggests that the two processes may rely on separate mechanisms, or it
could occur due to typical mental folding experiments utilising stimuli
for which each fold involves a fixed 90° transformation angle . The aim
of this study is to test the latter explanation. If varying the angle of
folding required coincides with changes to the magnitude of the
folding-related parietal negativity, mental folding can be viewed as a
series of rotations for the component parts of an object. Participants
will mentally fold a cube net to completion to decide whether two points
on the net will meet. In a 2x2 design, the cube nets will require
different numbers of folding (4 faces carried vs 6 faces carried), and
the folds will require different degrees of rotation to complete (50° vs
90°). Electroencephalography data will be analysed to determine the
presence of a transformation negativity over parietal leads between
400-800 ms. Greater negativity in this component for larger degrees of
folding angle will be taken as evidence for a shared mechanism between
mental folding and mental rotation.