Untersuchungen zur Kontextabhängigkeit der visuellen Objekterkennung

Recognizing a 3D object from 2D images seems easy and occurs
everyday, but it is in principle an ill-defined problem. Here we
report two behavioural experiments investigating how
representations of 3D objects are built under varying the
conditions of the recognition context, i.e. the set of test
objects, the prior object knowledge and the degree of stimulus
input information. We used a classification paradigm with initially
unknown, “structure only” classification criteria, consisting of a
category learning part and a subsequent generalization test. The
acquisition of prior object knowledge was varied with an
intra-modal (visual) group and a trans-modal (blindfold motor)
group. Results show that subjects are able to build structure-based
object representations from desultory 2D images. We observe a clear
context-dependency, i.e. the task was much more difficult without
prior object knowledge (control group) and for images with poor
stimulus input information. If, in the 2D image, alignment cues are
only sparsely available and thus the 3D object structure is
ambiguous, this lack of visual information can be trans-modally
compensated by motor prior knowledge which seems to be transferred
in real-time to the view-dependent representations. The results
further suggest the existence of several steps in the recognition
process: 1. Image understanding with generation of a hypothetical
object model. 2. Transformation and rotation in order to obtain a
matching with the image input signal (matching-to-fit-cycle). 3. If
step 2 is unsuccessful (e.g. mirror-symmetric objects), the
hypothetical object model is referred to an external reference.
These three steps are run through until the object is recognized
successfully (non-exhaustive search). Within this three-step
process the different, so far contradictory theories of object
recognition can be integrated, in that they seem to describe a
portion of the recognition process each.