Attention as Gatekeeper

Part Of: Attention sequence
Followup To: An Introduction to the Attentional Spotlight
Content Summary: 600 words, 6 min read

Global Workspace Theory

The weakest noticeable sound is defined at 0 decibels. Imagine putting somebody into a scanner, and having them listen to two sounds:

  1. A trumpet playing at -5 dB
  2. A trumpet playing at 5 dB

The acoustic difference between the two waveforms are not very different. How similar are the patterns of brain activation?

Attention- GWT

Here we see that subliminal auditory stimuli only activate early perceptual areas. Consciousness brings with it a huge increase in neural activation! Why should this be?

Global Workspace Theory (GWT) posits that consciousness is involved in two mental operations:

  • Binding: perceptual features, distributed across the brain, are bound together into discrete objects
  • Broadcasting: these object networks are broadcast to the rest of cortex, allowing consumer systems to use & modify them.

Attention- GWT Architecture
Three properties of consciousness have long baffled philosophers:

  • Consciousness is small: we can only retain a few (less than 7) objects in our head at one time.
  • Consciousness is serial: we can’t read two books at the same time.
  • Consciousness is flexible: unlike state of the art AI software, human reasoning can effortlessly enter new domains.  

GWT explains these facts. Consciousness is…

  • … small because it is hard to keep global object networks distinct from one another.
  • … serial because it is a singleton: massively parallel modules engage the same centralized resource.
  • … flexible because any consumer system can augment the processing of any perceptual object.

The Role of Attention

Attention is a gatekeeper. Our perceptual systems process myriad sensory events, these must bid for entry into the Global Workspace. The brain contains circuitry that implements this selective process, choosing which perceptual objects to bind & broadcast.  

Attention- Gatekeeper Role

Let’s see if we can use this metaphor to make sense of the sprawling literature on attention.

Consolidating Taxonomies

There are three taxonomies of attention that you’ll find in the literature:

  1. Covert vs overt attention. As discussed in Attentional Spotlight, we can differentiate attending to objects in the periphery, versus saccading to attended targets.
  2. Bottom-up vs top-down attention.  Distinguishes unplanned attention (e.g., to loud noises) vs goal-based attention (e.g., “count the number of times the soccer ball is passed”).
  3. Feature vs spatial attention. Distinguishes attending to a feature (“look for all red things”) vs an object (“look for a red triangle”)

In an influential paper, Peterson & Posner (1990) present three attentional networks: functionally independent brain systems which do attention. These are:

  1. Alerting. This network is tightly linked to wakefulness. Startling events induces strong alerting, lounging on a couch less so.
  2. Orienting. These two networks (one dorsal, the other located more ventral) orients the organism to process incoming stimuli.
  3. Executive. This network supports complex task execution, and goal-oriented attention.

Peterson & Posner’s framework allows us to simplify the conceptual landscape:

Attention- Taxonomy Reduction

The Orienting network produces Bottom-Up (“externally-driven”) attention. Its dorsal arm contains mechanisms for covert and overt orienting.

The Executive network produces Top-Down (“internally-generated”) attention. Feature and Object attention are both a form of search template, and as such are constructed here.

An Attentional Organ

In my next post, I’m going to argue that the Dorsal Orienting network is the attentional gateway, full stop. It alone performs selection: a single gateway through which percepts pass into conscious awareness.

On this model, the arousal, ventral orienting, and executive networks play auxiliary roles, modulating our brain’s attentional gateway.

Attention- Architecture Overview

Until next time.

References

  • Peterson & Posner (1990). The attention system of the human brain

[Sequence] Evans-Pritchard: Witchcraft, Oracles & Magic Among The Azande

azande

I read this classic text several years ago, and it left a lasting effect on me.

The Zande people are primarily a small-scale farming population located in central Africa. Their demographics are split between Democratic Republic of the Congo, in South Sudan, and the Central African Republic:

Zandeland_location

Evans-Pritchard briefly sketches Azande life in general, before zooming in on their complex religious system. At time of writing, 1937, these traditions had already begun to erode in the wake of European cultural imperialism. Racing against the clock, as it were, Evans-Pritchard managed to document the essence of these practices before they faded in the memories of the community.

Evans-Pritchard is a consummate professional, and this shows in his ethnographies. Azande culture and mysticism is explored in detail, and their customs – foreign to our ears – are treated largely without distracting judgment. Azande seeks spiritual answers from three kinds of oracles, each with increasing power: rubbing board, termite, and poison oracles. This practice was enmeshed in their legal system, their social structure, and their metaphysical beliefs. Azande culture further complemented these oracles by means of complex, interlocking theories of magic, and the social and medicinal contributions of a witch-doctor population:

Link: Summary

For me, the most interesting part of the book had to do with the relationship between mysticism and attention. Most of the following quotes relate to this.

Link: Quotes

To understand why it is that Azande do not draw from their observations the conclusions we would draw from the same evidence, we must realize that their attention is fixed on the mystical properties of the poison oracle and that its natural properties are of so little interest to them that they simply do not bother to consider them.

Observations such as the above suggest that disinterest in certain question-categories is not some random phenomenon that can be taken at face value. Azande individuals systematically experience disinterest in doubt-provoking challenges to their mystical ideology, and this “attention funnel” is anything but pre-meditated. Thus, attentional habits are not solely artifacts of personality: they also can be subpersonal, they are also influenced by culture: they do not necessarily serve the interests of their owners.

Finally, it would seem myopic to suppose that this quirk of human psychology is contained to this one culture. Perhaps this is enough to drive home my takeaway: treat disinterest with suspicion.