Olivier Georgeon's research blog—also known as the story of little Ernest, the developmental agent.

Keywords: situated cognition, constructivist learning, intrinsic motivation, bottom-up self-programming, individuation, theory of enaction, developmental learning, artificial sense-making, biologically inspired cognitive architectures, agnostic agents (without ontological assumptions about the environment).

Monday, March 28, 2011

Ernest 9.2 has a superior colliculus

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Ernest 9.2 has a visual resolution of 2 rows of 12 pixels. As before, Ernest can see above colored landmarks. The closest landmarks are seen in the first row, and possible landmarks behind these are seen above in the second row. Ernest 9.2's visual angular span equals 180°. As before, Ernest 9.2 cannot see through walls.

In this video, Ernest's half-circular head represents what Ernest sees. The first row is represented inside the half circle. The second row is represented on the half circle's crown. For example, on step 34, the inside of the half circle takes a light-green color because Ernest sees the square where it is standing, and the crown reflects the flower and the other squares that Ernest sees over the light-green square.

The environment is the same as with Ernest 9.1. The hive and the flowers are now represented as icons but Ernest distinguishes them only by their color and taste as before.

The most significant improvement is that Ernest 9.2 has a superior colliculus—a brain region also known as the tectum in the invertebrate. The superior colliculus maintains an internal retinotopic representation of the animal's surrounding environment. The superior colliculus is used to orient motivation and behavior towards a specific direction in the animal's egocentric referential (in some rudimentary vertebrates, like the hagfish, the superior colliculus constitutes the biggest brain region).

The effects of Ernest's colliculus are first seen on step 110. At this point, Ernest was heading toward the light-green square that was already known as leading to the flower field. On step 110, a flower appeared in the right side of the visual field. Because the flower was more motivating than the light-green square, the flower generated more activation in the colliculus's right side than that generated by the light-green square in the colliculus's center. This activation triggered a signal sent to the sequential system that caused Ernest to turn to the right towards the flower.

Ernest 9.2's initial phase of sensorymotor contigency learning lasts longer than before because of the increased complexity of the visual system. In this video, this initial learning phase roughly goes up to step 100. Once sensorymotor contingencies are learned, the pollen gathering is faster and steadier than with Ernest 9.1. Ernest 9.2 finishes gathering the five flowers on step 414, whereas Ernest 9.1 took 598 steps in the previous example run.

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