Playpen: Object Unit Demo
Purpose
This demo illustrates object units (OUs), processing
units with phase angles in addition to activation.
In-phase relationships between units represent features
belonging to the same object; out-of-phase relationships
represent features of different objects.
In the demo, you will see how positive weights between units
implement both excitation and phase-angle attraction and how
negative weights implement both inhibition and phase-angle
repulsion. When some units in the network have their
activations clamped, and the network is then allowed to
settle, the attraction and repulsion of phase angles
represents a simplified version of a model of object
segregation.
The Network
The network consists of a single layer of 49 units arranged in a
square and with built-in on-center off-surround weights
connecting the units. That is, each unit is joined by strong
positive connections to its neighbors and by weak negative
connections to other units in the network. The coupling
function relating units is the positive cosine function: .5 + .5
cos x.
This pattern of weights and this coupling function tend,
following settling, to result in one or more clusters of
activated units separated by unactivated gaps. Within each
cluster, the units tend to be in phase, and across the gaps they
tend to be out of phase.
What You Will See
- Note the on-center, off-surround weights connecting the
units by pressing the mouse button over a unit's square.
- When you do "Random activate", notice how clusters of
activated units with similar phase angles form.
- The test patterns for the network clamp the activation,
but not the phase angles, of units in opposite corners.
When you do "Test pattern", notice how most of the other
units remain inactive, how the phase angles within the
corner tend to agree, how the phase angles in opposite
corners tend to disagree, and how units close to the corners
may also be activated and aligned with the corner units.
Return to Playpen Technical Report 1
Michael
Gasser
Last modified: Tue Jun 24 01:22:32 EST