Editing Binding problem (section)

== Feature integration theory ==
=== Summary of problem ===
The visual feature binding problem refers to the question of why we do not confuse a red circle and a blue square with a blue circle and a red square. The understanding of the circuits in the brain stimulated for visual feature binding is increasing. A binding process is required for us to accurately encode various visual features in separate cortical areas.

In her feature integration theory, [[Anne Treisman|Treisman]] suggested that one of the first stages of binding between features is mediated by the features' links to a common location. The second stage is combining individual features of an object that requires attention, and selecting that object occurs within a "master map" of locations. Psychophysical demonstrations of binding failures under conditions of full attention provide support for the idea that binding is accomplished through common location tags.<ref>{{citation|author1=Treisman, A.|author2=Gelade, G.|year=1980|title=A feature integration theory of attention.|journal=Cognitive Psychology|volume=12|issue=1|pages=97–136|doi=10.1016/0010-0285(80)90005-5|pmid=7351125|s2cid=353246|url=http://homepage.psy.utexas.edu/homepage/class/Psy355/Gilden/treisman.pdf|archive-url=https://web.archive.org/web/20080905025042/http://homepage.psy.utexas.edu/homepage/class/Psy355/Gilden/treisman.pdf|archive-date=2008-09-05}}</ref>

An implication of these approaches is that sensory data such as color or motion may not normally exist in "unallocated" form. For [[Bjorn Merker|Merker]]:<ref name="Merker 2013">{{cite journal|author=Merker B|date=March 2013|title=Cortical gamma oscillations: the functional key is activation, not cognition|journal=Neurosci Biobehav Rev|volume=37|issue=3|pages=401–17|doi=10.1016/j.neubiorev.2013.01.013|pmid=23333264|s2cid=12661951}}</ref> "The 'red' of a red ball does not float disembodied in an abstract color space in [[Visual cortex#V4|V4]]." If color information allocated to a point in the visual field is converted directly, via the instantiation of some form of propositional logic (analogous to that used in computer design) into color information allocated to an "object identity" postulated by a top-down signal as suggested by Purves and Lotto (e.g. There is blue here + Object 1 is here = Object 1 is blue) no special computational task of "binding together" by means such as synchrony may exist. (Although Von der Malsburg<ref>{{cite book|last1=C. von der Malsburg|title=The what and why of binding: The modeler's perspective Neuron|date=1999|pages=95–104}}</ref> poses the problem in terms of binding "propositions" such as "triangle" and "top", these, in isolation, are not propositional.)

How signals in the brain come to have propositional content, or meaning, is a much larger issue. However, both Marr<ref>Marr, D. C. (1982) Vision. New York, Freeman.</ref> and Barlow<ref>{{cite journal|last1 = Barlow|first1 = H.|s2cid = 17487970|year = 1972|title = Single units and sensation: A neuron doctrine for perceptual psychology?|journal = Perception|volume = 1|issue = 4|pages = 371–394|doi=10.1068/p010371|pmid = 4377168|doi-access = free}}</ref> suggested, on the basis of what was known about neural connectivity in the 1970s that the final integration of features into a percept would be expected to resemble the way words operate in sentences.

The role of synchrony in segregational binding remains controversial. Merker<ref name="Merker 2013"/> has recently suggested that synchrony may be a feature of areas of activation in the brain that relates to an "infrastructural" feature of the computational system analogous to increased oxygen demand indicated via BOLD signal contrast imaging. Apparent specific correlations with segregational tasks may be explainable on the basis of interconnectivity of the areas involved. As a possible manifestation of a need to balance excitation and inhibition over time it might be expected to be associated with reciprocal re-entrant circuits as in the model of [[Anil Seth]].<ref name="Seth 2004"/> (Merker gives the analogy of the whistle from an audio amplifier receiving its own output.)

=== Experimental work ===
Visual feature binding is suggested to have a selective attention to the locations of the objects. If indeed spatial attention does play a role in binding integration it will do so primarily when object location acts as a binding cue. A study's findings have shown that functional MRI images indicate regions of the parietal cortex involved in spatial attention, engaged in feature conjunction tasks in single feature tasks. The task involved multiple objects being shown simultaneously at different locations which activated the parietal cortex, whereas when multiple objects are shown sequentially at the same location the parietal cortex was less engaged.<ref>{{cite journal|last1=Shafritz|first1=Keith M.|last2=Gore|first2=John C.|last3=Marois|first3=René|title=The role of the parietal cortex in visual feature binding|journal=Proceedings of the National Academy of Sciences|pages=10917–10922|language=en|doi=10.1073/pnas.152694799|date=6 August 2002|volume=99|issue=16|pmid=12149449|pmc=125073|bibcode=2002PNAS...9910917S|doi-access=free}}</ref>

==== Behavioral experiments ====
Dezfouli et al. investigated feature binding through two feature dimensions to disambiguate whether a specific combination of color and motion direction is perceived as bound or unbound. Two behaviorally relevant features, including color and motion belonging to the same object, are defined as the "bound" condition, whereas the "unbound" condition has features that belong to different objects. Local field potentials were recorded from the lateral prefrontal cortex (lPFC) in monkeys and were monitored during different stimulus configurations. The findings suggest a neural representation of visual feature binding in 4 to 12 Hertz [[frequency bands]]. It is also suggested that transmission of binding information is relayed through different lPFC neural subpopulations. The data shows behavioral relevance of binding information that is linked to the animal's reaction time. This includes the involvement of the prefrontal cortex targeted by the dorsal and ventral visual streams in binding visual features from different dimensions (color and motion).<ref>{{cite journal|last1=Parto Dezfouli|first1=Mohsen|last2=Schwedhelm|first2=Philipp|last3=Wibral|first3=Michael|last4=Treue|first4=Stefan|last5=Daliri|first5=Mohammad Reza|last6=Esghaei|first6=Moein|title=A neural correlate of visual feature binding in primate lateral prefrontal cortex|journal=NeuroImage|pages=117757|language=en|doi=10.1016/j.neuroimage.2021.117757|date=1 April 2021|volume=229|pmid=33460801|s2cid=231607062|doi-access=free}}</ref>

It is suggested that the visual feature binding consists of two different mechanisms in visual perception. One mechanism consists of agonistic familiarity of possible combinations of features integrating several temporal integration windows. It is speculated that this process is mediated by neural synchronization processes and temporal synchronization in the visual cortex. The second mechanism is mediated by familiarity with the stimulus and is provided by attentional top-down support from familiar objects.<ref>{{cite web|last1=Bernhard|first1=Hommel|title=When an object is more than a binding of its features: Evidence for two mechanisms of visual feature integration|url=https://bernhard-hommel.eu/Integrating%20features%20and%20objects.pdf|website=Psychology Press|publisher=Leiden University Institute for Psychological Research, and Leiden Institute for Brain and Cognition, Leiden, The Netherlands}}</ref>