James R. Pomerantz

Abstract
Garner Interference (GI) has been shown to measure the grouping of lines into unitary
perceptual configurations. E.g., when Ss classify curved line pairs such as ((, (), )(, and ))
on the basis of one line, RTs rise sharply when the other varies orthogonally. Altering
the lines’ positions (and thus perceived grouping) changes their GI levels in an orderly
fashion. We extend these findings to simpler forms of perceptual organization with just
two dots in the field, and we discuss GI’s potential to identify such emergent features as
symmetry, collinearity, parallelism, closure, relatability, intersections, terminators and
edges. Lastly, we contrast GI with other diagnostics for grouping, and we ask whether GI
results from a failure to focus attention.