evolution of consciousness: a new view (Introduction)

by David Turell , Sunday, March 12, 2023, 20:03 (620 days ago) @ David Turell

Temporal view of consciousness:

https://inference-review.com/letter/on-the-temporal-structure-of-consciousness

"We usually believe, for example, that consciousness is continuous. We perceive the trajectory of a diver on her way down in the ocean seemingly at each moment of time. However, simple considerations and experiments show that perception is discrete rather than continuous—that is, consciousness occurs only at certain moments of time.

"How can discrete perception be explained? The classic idea is that there are moments of time during which perception is constant, similar to the frames in a movie where each frame shows only a snapshot of the world. In this scenario, motion is detected by comparing the differences between frames. There is no motion, no change, no processing within a single frame. It is often proposed that perception is not only discrete, but also rhythmic. Perception occurs with a fixed sampling rate of, for example, 10Hz, meaning that there is a new frame every 100ms. Staying with the movie metaphor: think of a surveillance camera that takes snapshots at a fixed rate. What happens in between the snapshots is lost, except for parts that may be carried over as artifacts on the camera’s sensors—so-called neural persistence—and bleed into the next frame.

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"We propose that only consciousness is discrete. Unconscious processing, to the contrary, is continuous, sophisticated, and has high spatiotemporal resolution. This is very different from simplistic neural persistence—which would add up all information during a perceptual moment into a useless superimposed image, similar to when the shutter of a camera opens for too long. In our model, motion is processed unconsciously by motion detectors, of which only the output is consciously perceived at the end of an unconscious processing period. Thus, we do not perceive motion while it happens in the world, nor while it is computed by motion detectors. Instead, we perceive the output of the motion detectors much later...we do not perceive the motion exactly when it happens in the world, which is obvious, since neural processing takes time. We do not perceive motion exactly when neurons are reflecting the diver’s position. Rather, information about the diver’s trajectory is integrated over a substantial period of time, and we perceive the resulting motion after these computations are completed.

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"We propose that entire events—e.g., a diver who jumped from a high cliff following a parabolic trajectory in the blue sky, are processed unconsciously, and rendered conscious at one discrete moment of time. Thus, there is no comparison across frames. In addition, unconscious processing does not stop at the end of a moment, it goes on continuously without breaks. Only the conscious “readouts” occur at certain moments of time. Importantly, our model is not rhythmic. We have shown that the duration of a conscious percept depends on the processing load: the higher, the longer.

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"... our model implies that most of actions are executed unconsciously. We do not see any problem here concerning free will, which we argue operates on much longer time scales. For example, we want to engage in a soccer game. This is free will. We chose to start running upfield. This is also free will. In contrast, fast reactive actions during the game are usually executed unconsciously—in accordance with our will. If the unconsciously triggered action goes against our will, we consciously perceive the mistaken action and that it was against our will—at the next conscious update. In general, we propose that actions become part of the following conscious percept. Actions are part of the event that we perceive. As another example, when we catch a falling plate before it hits the ground, and in other situations where we make ultra-quick decisions, we cannot usually tell why, when, or how the action was triggered. This is because processing was unconscious.

"To reconcile our findings of long discrete unconscious periods with the shorter periods he and others have found, VanRullen proposes a 3-stage model: stage 1 corresponds to unconscious processing, stage 2 to classic discrete snapshots of 100ms corresponding to short instable conscious percepts, and stage 3 is a consolidated percept that comes several hundreds of milliseconds later. The instable percept of stage 2 can be overwritten and may be lost in the consolidated memory of stage 3. VanRullen identifies stage 2 with phenomenological consciousness, and stage 3 with access consciousness. Although we cannot rule out such a model, and are even partly sympathetic to it, we propose that there are no snapshots, but ongoing unconscious processing instead.

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"Phenomenal consciousness, for example, may simply reflect the unconscious processing of objects, which are not (yet) conscious, but can strongly influence actions. Whatever the final answer is, a conceptual distinction between short term processing in the range of 100ms and longer discrete updates occurring every few hundred ms seems necessary to account for current empirical evidence regarding the temporal structure of consciousness.

Comment: Yes we see a motion picture in temporal or phenomenological consciousness. This only points out again my point that the brain is evolved to give us a desired continuous picture of reality, while the brain itself is stringing together unconsciously a series of electronic signals."