A (Somewhat) New Solution to the Variable Binding Problem

Abstract

To perform automatic, unconscious inference, the human brain must solve the "binding problem" by correctly grouping properties with objects. Temporal binding models like SHRUTI already suggest much of how this might be done in a connectionist and localist way by using temporal synchrony. We propose a set of alternatives to temporal synchrony mechanisms that instead use short signatures. This serves two functions: it allows us explore an additional biologically plausible alternative, and it allows us to extend and improve the capabilities of these models. These extensions model the human ability to both perform unification and handle multiple instantiations of logical terms. To verify our model's feasibility, we simulate it with a computer system modeling simple, neuron-like computations.

The neural binding problem(s)

“…As discussed in the previous section, decades of research have yet to find convincing evidence for temporal phase binding and people continue to explore possible alternatives. One recent effort (Barrett et al 2008), attempts to combine many of the ideas of Shruti with a basic variable binding mechanism closer to the signature method. Like Shruti they begin with the fact that people can only deal with a small number (*7) of bindings at a time.…”

“…To link the short signatures to the (still) large number of possible concepts, Barrett et al (2008) uses a central structure that controls binding. This also enables some operations that Shruti cannot perform.…”

Ecological expected utility and the mythical neural code

“…The basic and easier binding problem concerns how we can coherently see a bouncing red ball and a blue book given that these properties are computed in separate brain areas. The harder, variable binding , problem involves how we remember and draw inferences from complex relations (Barrett et al 2008). For example, the sentence “John gave the book to Dick and the red thing to Jane” automatically leads to inferences about who has what (Shastri 2001).…”

“…When our sample sentence was heard, the system would just add the new ownership facts to the appropriate phase. Such a system is computationally feasible and has been extensively discussed (Barrett et al 2008). But despite some suggestive early experimental findings, there is good evidence (Shadlen and Movshon 1999) that this is not the mechanism that the brain employs.…”

Perception, Memory, and Duration: The Binding Problem and the Synthesis of the Past

“…Quantum entanglement has been advanced to solve the problem, in connection with new findings in split-brain surgery and in relations between cytoskeleton and synapse (Georgiev, 2003). Other solutions can be found in the literature (Rado and Scott, 1996;Barrett et al, 1998). In spite of the ingenuity of many of these solutions and the recourse of most to deep computer power, it is fair to say that each has significant weakness and no one is yet universally accepted.…”