Cognition Through Imagination and Affect

1
Cognition Through Imagination and Affect

• Murray Shanahan
• Imperial College London
• Department of Computing

2
Overview

• Brain-inspired architectures
• Cognitively mediated action
• An internal sensorimotor loop

3
Brain-inspired Architectures

• Progress towards the vision of human-level AI has
  been slow
• Classical AI has not yet succeeded in devising
  systems that can match the common sense reasoning
  skills of a young child
• Biologically-inspired AI has been very slow to
  move beyond trivial motor tasks and tackle the
  difficult questions of cognition
• Some researchers are now turning to the human
  brain for inspiration, especially to
  architecture-level theories of its functioning

4
A New Vocabulary

• We have a whole new set of concepts to explore
• But all should be in scare quotes
• Many are alien to both top-down classical AI and
  bottom-up biologically-inspired AI
• Imagination
• Emotion
• Consciousness
• Or, more technically
• Internally closed sensorimotor loops
• Affect-based mechanisms of selection
• Global workspaces

5
Imagination and Affect

• Here we have an internally-closed sensorimotor
  loop that can simulate interaction with the
  environment

• It rehearses trajectories through sensorimotor
  space without having to traverse those
  trajectories for real
• The outcome of various potential trajectories can
  be evaluated. This where affect comes in
• The result impacts on action selection

6
Why an Internal Loop?

• The inner sensorimotor loop implements a form of
  analogical representation
• The medium of representation has the same
  structure as what is being represented eg a
  map
• We get spatial properties for free, and complex
  shapes can be represented
• The dynamics of the inner loop has a close
  relationship to the dynamics of the outer loop
• It can realise inner speech as well as mental
  imagery
• Categories become attractors in a state space
  having same structure as that of sensory input
• This addresses the symbol grounding problem

7
A Cognitively-mediated Action

• On sight of green, turn-right is action has
  highest salience
• But this reactive response is held on veto while
  turning right is rehearsed

• Sight of red of predicted
• But red is aversive
• So salience of turn-right is modulated down,
  resulting in turn-left becoming the action with
  highest salience
• Again this response is held on veto

• Now sight of blue is predicted, and blue is
  associated with reward
• So salience of turn-left is modulated up
• Eventually it reaches a threshold, veto is
  released, and robot acts

8
The Core Circuit
VC / IT visual cortex / inferior temporal
cortex AC association cortex GW / BG
global workspace / basal ganglia Am
amygdala
This core circuit combines an internal
sensorimotor loop with mechanisms for broadcast
and competition, and thereby marries the
simulation hypothesis with global workspace theory
9
Affect Circuitry (Am)
VC / IT visual cortex / infero-temporal cortex,
BG basal ganglia, GW global workspace
10
Motor Circuitry
MC motor cortex BG basal ganglia Am
amygdala
11
Concluding Remarks

• The brain-inspired approach to building cognitive
  systems is promising
• But it is still relatively unexplored
• Affect plays a vital role in the proposed
  architecture
• It is currently a simple scalar value. A vector
  of basic emotions would be interesting to
  investigate
• The relationship to consciousness is very
  interesting
• Too bad theres no time to talk about it ?

Shanahan, M.P. (2006). A Cognitive Architecture
that Combines Inner Rehearsal with a Global
Workspace. Consciousness and Cognition 15,
433449.