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).

Tuesday, April 26, 2011

Ernest 10.1's activity traces

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Thanks to Pierre-Yves Ronot, we can now see Ernest's activity traces in real time.

In this video, the lower part of the trace shows Ernest's visual field. Visual pixels are represented as little rectangles when Ernest is moving forward, and as little trapezoids when Ernest is turning. Vertical red lines across the visual field indicate that Ernest is bumping into a wall. Blue circles indicate that he is eating a fish. The trace shows the different items in the environment going back and forth through the visual field as Ernest is moving.

We can see the initial phase of sensorymotor learning (steps 0-90) during which Ernest is often bumping into walls. Notably, his visual apparatus does not inform him about his distance to walls.

The line at the upper part of the trace takes the color of the item that recieves Ernest's current attention. This item of visual attention is also indicated by the "pie" in the local map as reported in the previous post.

For example, before eating his first fish, Ernest is distracted by other items (see steps 90 to 99). After having tasted a fish, however, Ernest focuses on fish whenever he sees them (steps 148 to 166).

Traces help us understand how Ernest sees his world. Ernest receives no other information from the world than that displayed in the trace. Traces also represent Ernest's experience that he encodes in his episodic memory. The encoding of experience in the form of activity episodes constitutes the base of Ernest's learning.

Monday, April 25, 2011

Ernest 10.1 constructs a local map of his environment

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Ernest 10.1 associates co-occurring sensory stimulations together into bundles. A bundle is a set of sensory stimulations that denotes an object in the world. By constructing bundles, Ernest starts to perform multi-modal sensory integration.

We assume that a bundle can represent a unique kind of object in the world. We drew this assumption from David Hume's bundle theory of objects. This theory postulates that objects consist only of the set (bundle) of their observable properties.

Additionally, Ernest 10.1 constructs a local map of the bundles surrounding him. In this video, the local map is displayed in cell k6 (next to the cycle counter). The local map represents Ernest's awareness of his local surrounding. The top of the map corresponds to the front of Ernest. Ernest's current visual stimulation is represented as a "pie" over the map.

The local map is based on Ernest's somatotopic map. A bundle is learned by associating the tactile stimulation in front of Ernest (the center-top cell in the somatotopic map) with the simultaneous visual stimulation (the "pie"). As he moves, Ernest is then able to follow the newly-created (or recognized) bundle in the somatotopic map.

For example, Ernest creates a bundle for the yellow square on step 27. Then, on step 28, this bundle moves to the center of the map; on step 30, to the center-rear of the map; and, on step 31, to the left-rear corner of the map (the local map is displayed with a delay of one cycle).

When Ernest eats, he associates his gustatory stimulation with the bundle that represents where he is standing, that is, the "fish bundle" that was previously constructed from visual and tactile stimulations. This delicious taste associated with fish then makes Ernest's prefer pursuing fish rather than alga in subsequent activity.

Apart from his still-unexploited local map, and from the fact that his visual field was reduced to a single row of 12 pixels, Ernest 10.1 is the same as poor Ernest 9.3. We now need to investigate how Ernest would use his local map.

Friday, April 8, 2011

Ernest 10.0 has a somatotopic map

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Ernest 10.0 is a shark. Sharks are archaic vertebrates whose brain didn't evolve much over the last 450 million years or so. Yet, a shark's brain contains the same set of basic anatomical components as modern vertebrates' brains (Brain, Wikipdia).

In particular, Ernest 10.0 has a somatotopic map—a brain area that represents Ernest's body in an isomorphic way. In humans, this area would correspond to the postcentral gyrus, also known as the primary somatosensory cortex.

In this video, Ernest's somatotopic map is represented as a grayscale grid over Ernest's body. This grid has 9 cells that represent what Ernest touches in the 8 surrounding squares plus the square where he is standing.

Each cell in the somatotopic map can reflect three different kinds of tactile feelings:
- light gray: only water.
- medium gray: something soft, an alga or a fish that Ernest can swim over.
- black: something hard, a wall or the aquarium's side (the central cell is never black because Ernest cannot stand on a wall).

We hypothesize that the somatotopic map will be useful for acquiring a sense of space, although we don't yet know exactly how. We drew this hypothesis from the idea that our sense of space comes from the mere fact that our body occupies space. We, however, could not find much arguments in the literature to support this hypothesis.

Apart from his still-unexploited somatotopic map, and from the fact that he is always hungry for fish, Ernest 10.0 is the same as poor Ernest 9.3. This video shows how miserable he is. He has no sense of space and he is even unable to "simplify" a sequence consisting or turning six times 45° clockwise into a sequence consisting of turning twice 45° counterclockwise (see steps 267 or 279).

Tuesday, April 5, 2011

Poor Ernest 9.3

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On step 406, we removed the yellow-green landmark that Ernest was using to find his way towards the southeast field. This leaves poor Ernest spinning in place, miserably goalless.

To explore space in the absence of landmarks, Ernest will need some skills to construct a spatial representation of the environment. Such skills are exhibited by most vertebrates and are believed to involve some basic components of the vertebrate's brain. We now need to explore the role of these components.

Friday, April 1, 2011

Ernest 9.3

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The colliculus activation algorithm has been improved. This gives Ernest 9.3 a smoother behavior than Ernest 9.2 (e.g., see the elegant curve taken on the way back to the hive on steps 356-388).

In addition, Ernest's thorax now takes the color of the most motivating landmark in the visual field—the landmark that raises the most activation in the colliculus. This landmark is the object of Ernest's current attention and drives Ernest's homing tendency.

At the beginning, Ernest is seeking to gather pollen but he does not know how to distinguish flowers from other landmarks. The highest activation is only given by the largest landmark in the visual field (i.e., the closest landmark). This causes Ernest to visit all landmarks randomly. When a landmark is visited, this landmark's activation is lowered for some time, meaning that Ernest temporarily looses interest in this landmark. This causes Ernest to move on to another landmark.

On step 38, Ernest finds a landmark from which he can gather the pollen (the blue flower). This switches his motivation to make him seek for the hive. In the hive-seeking motivational mode, landmarks raise an additional activation that is proportional to their proximity to the hive (or to Ernest's place of birth) as much as Ernest remembers from his way out. This activation mechanism causes Ernest to go back to the yellow square by traveling from known landmarks to known landmarks. After reaching the yellow square (step 83) he finds no more motivating landmarks and starts a random exploration again until he finds the hive for the first time on step 94.

When on the hive, Ernest drops the pollen and switches back to the pollen-seeking motivational mode. Now, the highest activation is generated by landmarks that Ernest remembers as being the closest to the pollen. This leads Ernest back to the northeast flower field. On the second way back, Ernest is now able to recognize the hive, which causes him to turn directly towards the hive on step 159 (by-passing the yellow square).

When the northeast flower field is empty, Ernest fumbles again until he sees new landmarks to explore (green landmarks in the southeast field on step 311). From then on, he starts exploiting the southeast field the same way he exploited the northeast field.