An analysis of Treisman’s solution to the Binding Problem – Part 2.

<I’ve decided to make this post a lot less technical and shorter upon feedback>

In my last post, I talked about The Binding problem itself and discussed some suggested solutions and where they failed. In this post, I’ll be discussing Anne Treisman’s proposed solution as per her paper titled Feature Binding, Attention and Object Perception.

Just to recap, the binding problem arises as a consequence of the possibility of us mismatching the different characteristics and objects. In other words, the binding problem questions how we match the various characteristics of different objects that we see on a daily, continuous basis accurately and seamlessly.  

Let us now consider Treisman’s proposed mechanism. Now, the star in Treisman’s theory is visual spatial attention. So, before we look at the actual theory, let us discuss what spatial attention exactly is.

Visual spatial attention

Visual spatial attention (perhaps self-evidently) describes how humans pay attention by attributing priority to location. This would probably be better explained if we define what visual attention is. Think of it as a sieve. It takes the rich visual world as input but only let’s a particular object (which is the object that we colloquially say that we “pay attention to”) pass through. This is the object of our attention. This object is then brought into working memory for further processing. Now, this sieve needs a criterion to sieve visual information. What will it let pass the sieve? Visual spatial attention says that this criterion is space/location. Only the object in a particular location is passed into working memory through attention.

Treisman’s solution

Treisman proposes a mechanism in which with spatial attention, we can code for(bind) a single object at a time which removes the problems associated with mismatching characteristics of different objects. This is because, our spatial attention can filter out a singular object, and while ignoring all other objects or stimuli, we can effectively bind of different features of the selected object to that itself.

Illusory Conjunctions

An interesting empirical result that Treisman shows in support of this theory is that of “Illusory Conjunctions”.

Illusory conjunctions happen when in perceiving different objects, we wrongly combine the features of them. (Essentially, this is the failure of whatever binding mechanism our brain operates with. Since our quest is to figure out this mechanism, examining its failure is – as proven in Treisman’s case – a worthwhile undertaking.)

In the empirical study conducted by Treisman, a sample of test subjects were provided a display with four shapes with different characteristics sandwiched between two black numbers.

A binding error (or an illusory conjunction) would occur when subjects reported seeing a yellow triangle, or a red circle which meant that they were mismatching features with objects.

The sample of subjects were asked to perform a variety of tasks in a short amount of time; They had to simultaneously

1. Identify and report the digits

2. Report all other features they could identify with one of the four shapes that were distinguished for them by a marker that flashed 200ms after the display went on.

In such a way, they were unable to focus attention on a particular object but spread their attention all over the display: they had to focus on the numbers, as well as the marked shape. The experiment found a statistically significant number of binding errors (Illusory Conjunctions) by mismatching features and objects.

To make sure that their inability to focus is what lead to the illusory conjunction a separate experiment where the marker flashed 150ms before the display went on and numbers need not be reported was conducted. This allowed subjects to be able to direct attention to the marked object. Accordingly, this experiment found no significant binding errors.

There are so many other cool empirical results cited in the paper. If you’re interested, click here for the article. I’d recommend it; it’s a good read and not too complex either. I’d assume it to be a pretty manageable read for non-experts. I was a complete novice when I first read it for my intro to cog sci class and I found it quite manageable. I did spend some time on it though, looking up jargon and stuff, but it wasn’t too bad – especially if you read it after reading my posts.

That concludes my two-part post on Tresiman and the Binding problem. So, I guess this is goodbye.

Till my next post!

P.s. I hope this post is slightly less jargon-y. I tried to make it an easier read upon feedback.

References:

1. Treisman, A. (1998). Feature Binding, Attention and Object Perception. Philosophical Transactions: Biological Sciences, 353(1373), 1295-1306. Retrieved May 25, 2020, from www.jstor.org/stable/56884
2. Treisman, Anne, and Hilary Schmidt. “Illusory Conjunctions in the Perception of Objects.” Cognitive Psychology, vol. 14, no. 1, 1982, pp. 107–141., doi:10.1016/0010-0285(82)90006-8.
3. Kawamura, Kazuhiko, et al. “Implementation of Cognitive Controls for Robots.” Household Service Robotics, 2015, pp. 429–454., doi:10.1016/b978-0-12-800881-2.00019-0.