Ch. 2

• Physical events influence perception.
• The perceptual process begins with seeing in focus, seeing in dim light, and seeing in fine details.
• Snakes can 'see' in the dark thanks to protein channels that are activated by heat from the bodies of their prey.
• Vipers, pythons and boas have holes on their faces called pit organs, which contain a membrane that can detect infrared radiation from warm bodies up to one meter away.
• Sparse Coding: occurs when a particular stimulus is represented by a pattern of firing of only a small group of neurons, with most neurons remaining silent

  • different neurons will encode different features
• Structural connectivity is the “road map” of fibers connecting different areas of the brain.
• Functional connectivity is the neural activity associated with a particular function that is flowing through this structural network.
• Population coding: proposes that our experiences are represented by the pattern of firing across a large number of neurons

  • most believed to be true today
  • idea that neurons are tuned to a range of stimuli
  • much more flexible
  • allows you to account for a large number of faces/objects without needing a single neuron for everything
• Specificity Coding: a specialized neuron that responds only to one concept or stimulus

  • problem with this theory as it doesn't explain how we learn about new objects never seen before
• Both grating and gray fields have the same average light intensity.
• Distributed Representation: the idea that the brain represents information in patterns distributed across the cortex, not just one brain area.
• An experimenter, blinded to the side of the grating, observes through a peephole.
• Inhibitory transmitters cause hyperpolarization, decreasing the likelihood of an action potential.
• Testing an infant with the preferential looking technique involves the mother holding the infant in front of a display, with the display featuring a grating on the right and a homogeneous gray field on the left.
• Research has shown that connections between brain areas may be just as important for perception as the activity in each of those areas alone.
• Distributed representation focuses on the activity in multiple brain areas and the connections between those areas.
• The experimenter judges whether the infant looks left or right.
• Neurotransmitters are released by the presynaptic neuron from vesicles, received by the postsynaptic neuron on receptor sites, matched, like a key to a lock, into specific receptor sites, and used as triggers for voltage change in the postsynaptic neuron.
• Excitatory transmitters cause depolarization, increasing the likelihood of an action potential.
• The blind spot is a location in the eye where no receptors are present.
• The Fermi Gamma-Ray Space Telescope is an example of an eye-like instrument.
• The location and number of rod and cone receptors in the eye determine visual acuity.
• Infrared cameras work similarly to the pit organs of snakes, allowing them to 'see' an image of their predator or prey.
• Fermi Gamma-Ray Space Telescope is an example of an eye-like instrument.
• Myopia, hyperopia, and presbyopia are examples of visual disorders.
• Focusing light onto receptors is
• At night, the pit organs allow snakes to 'see' an image of their predator or prey — as an infrared camera does — giving them a unique extra sense.
• Focusing light onto receptors is a crucial aspect of vision.
• Myopia (nearsightedness): trouble seeing distant objects
• Refracted Myopia: cornea and lens overbend the light
• Axial Myopia: eyeball is too long
• Hyperopia (farsightedness): trouble seeing near objects

  • focus point beyond retina
  • eyeball too short
• Presbyopia: trouble seeing near objects due to aging

  • lens becomes more rigid with age
• Transduction: the conversion of one form of energy to another

  • into action potentials
• When light hits photoreceptors, there's a transformation in the opsin-retinol complex in that the retinol undergoes transformation in it's shape, called Isomerization (change in shape to the protein)
• Rods and cones have different sensitivities to the isomerization process
• Odorants: chemicals that emanate from substances
• Bleaching: (temporary) destruction of the opsin & retinal

  • when bleached, photoreceptors no longer function
• • Rods are easily bleached by high levels of light - photo pigment gets regenerated in low light (until max)
  • Cones are also bleached by high level of light - photo pigment recovers quickly from bleaching process
• Dark Adaptation: ability to adapt to low light conditions

  • vision gets better