Ep 87 "How do we operate in the present when we perceive the past?"
Jan 13, 2025
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Explore how our brains process visual signals, making us slightly live in the past, yet still manage to catch a baseball. Discover the fascinating world of optical illusions and how our expectations shape perception. Unravel the concept of self-tickling and its surprising links to schizophrenia. Dive into the brain's predictive abilities, as it creates internal models to navigate reality despite sensory delays. Experience the interplay between motion and perception through relatable scenarios, like driving in a bustling city.
The brain constructs perception by predicting sensory inputs based on prior knowledge, illustrating its active role in interpreting reality.
Visual illusions highlight how expectations shape our perception, revealing the complex interplay between sensory processing and consciousness.
Deep dives
Understanding Visual Illusions
Visual illusions can reveal significant insights about how the brain constructs perception. When observing images of seemingly random blobs, people often fail to see the intended shapes until given context—demonstrating that perception relies heavily on expectations. This illustrates that the brain interprets visual stimuli based on prior knowledge, affecting what we perceive as reality. The understanding of these illusions raises questions about our awareness of how consciousness shapes our perception of the world.
The Brain's Predictive Model
The brain does not merely process incoming sensory information; instead, it actively predicts what we should see based on internal models. These models adjust as the brain compares sensory inputs with expectations, refining its representation of reality. For instance, when capturing a moving object, the brain anticipates its future position instead of reacting after the fact, which is crucial for actions like catching a baseball. This predictive mechanism is essential for functioning efficiently in a world where sensory information often arrives too late.
The Role of the Thalamus
Understanding the connectivity between the retina, thalamus, and visual cortex is fundamental to grasping how visual processing works. Instead of a straightforward path for visual information, signals undergo a complex journey where expectations from the cortex inform the thalamus about what to look for. Only unexpected differences between predicted and actual input are conveyed to the visual cortex, allowing for constant updates to our internal model. This pathway sheds light on how the brain efficiently deals with the delays inherent in sensory processing.
Implications of Perception in Real Life
The predictive nature of perception has practical implications for everyday activities like navigating through a crowded space. When surrounded by moving people, the brain utilizes experience to forecast their movements, allowing for smooth navigation without constant visual confirmation. The evolution of this capability highlights its survival advantage, enabling quick reactions to potential threats or opportunities. Overall, this understanding emphasizes the brain's complex yet efficient processing methods that go beyond simple reactionary behavior.
Because visual signals take time to process, we live slightly in the past. So how do we ever catch a baseball? And what does this have to do with certain visual illusions, or the view in New York City, or the things you were never taught in school, or the warp drive in Star Trek? Join Eagleman this week for a mind blowing look at the strange relationship between vision and time.
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