PSYC 4415 Test 1 Study Guide PDF

PSYC 4415 Test 1 Study Guide Chapter 1: Psychophysics and Neuroscience Foundations 1.​ What is the difference between distal and proximal stimuli? Distal stimuli refer to the actual object or event in the world, while proximal stimuli are the physical phenomena produced by the distal stimulu...

PSYC 4415 Test 1 Study Guide Chapter 1: Psychophysics and Neuroscience Foundations 1.​ What is the difference between distal and proximal stimuli? Distal stimuli refer to the actual object or event in the world, while proximal stimuli are the physical phenomena produced by the distal stimulus that interacts with sensory receptors​. 2.​ What is an absolute threshold, and how does it differ from a difference threshold? An absolute threshold is the minimum intensity of a stimulus needed for detection, whereas a difference threshold (JND) is the smallest detectable difference between two stimuli​. 3.​ What is the difference between top-down and bottom-up processing in perception? Top-down processing involves perception influenced by prior knowledge and expectations, while bottom-up processing is driven purely by sensory input​. 4.​ According to the law of specific nerve energies, how does the brain interpret sensory signals? The brain interprets sensory signals based on which neurons are activated, not the stimulus itself​. 5.​ What does the neuron doctrine state about perception? Perception arises from the combined activity of specialized neurons, each responding to specific features​.  6.​ What is the typical function of dendrites? Dendrites receive signals from other neurons. 7.​ What is the typical function of axons? Axons transmit signals from the neuron to other cells​ 8.​ What is the typical resting membrane potential of a neuron in the brain? The typical resting membrane potential of a neuron in the brain is -70 mV. 9.​ Which ions are more concentrated inside vs. outside a neuron at rest? Potassium (K⁺) is more concentrated inside the neuron, while sodium (Na⁺) and calcium (Ca²⁺) are more concentrated outside​. 10.​What is an EPSP, and how does it influence the postsynaptic neuron? An EPSP is a depolarizing event that increases the likelihood of an action potential in the postsynaptic neuron​. 11.​What are voltage-gated ion channels, and what role do they play in neural transmission? These channels open or close based on changes in membrane potential, playing an important role in the generation and propagation of action potentials​. Chapter 2: Light and the Eyes 1.​ What is a photon, and why is it significant in vision? A photon is a particle of light that interacts with photoreceptors in the retina to initiate vision​. 2.​ How do photons interact with photoreceptors in the retina? Photons trigger chemical changes in photoreceptors, initiating neural signals. 3.​ What type of electromagnetic radiation is visible to the human eye? The human eye can perceive wavelengths between approximately 400-700 nanometers. 4.​ How does the lens adjust to focus on objects at different distances? The lens changes shape to focus light on the retina for objects at different distances​. 5.​ How do a strong lens and a weak lens differ in terms of focal length and refraction angle? A strong lens has a short focal length and refracts light sharply, making it suitable for close objects, while a weak lens has a longer focal length for distant objects​. 6.​ Where are cones most densely packed in the retina? Cones are densely packed in the fovea​.  7.​ Where are rods most densely located, and what is their primary function? Rods are most densely located in the periphery of the retina and function primarily in low-light conditions. 8.​ How do sensory receptors convert proximal stimuli into neural signals? Sensory receptors convert proximal stimuli into neural signals through transduction. 9.​ How does an on-center RGC respond to light? On-center RGCs increase firing when light hits the center of their receptive field. This contrast-detection enhances edge perception and visual clarity. Light in the center → strong firing (excitatory response) Light in the surround → inhibited firing (suppresses activity) Light in both the center & surround → weak response (signals cancel out) 10.​How does an off-center RGC respond to light? Meanwhile, off-center RGCs respond to light in the opposite way of an on-center RGC. This enhances contrast detection, helping the brain perceive dark objects on bright backgrounds and improving edge detection in vision. Light in the center → decrease firing (inhibited by ON-cone bipolar cells, reduced excitation from OFF-cone bipolar cells) Light in the surround → increase firing (excited when the surround is illuminated) Light in both the center & surround → weak response (signals cancel out) 11.​What happens when light strikes both the center and surround of a ganglion cell’s receptive field? Simultaneous light in the center and surround of an RGC's receptive field can neutralize the response. 12.​Which retinal cells send action potentials to the brain? Retinal ganglion cells send action potentials to the brain​. 13.​What is retinotopic mapping, and why is it important in the visual system? This refers to the spatial arrangement of neurons in the brain corresponding to the retina's layout​. 14.​What is the difference between actual physical intensity and perceived intensity in the context of Mach bands? Mach bands demonstrate how perceived intensity contrasts are exaggerated at edges, differing from the actual physical intensity​. Chapter 3: The Visual Brain 1.​ What is the role of the lateral geniculate nucleus (LGN) in visual processing? The lateral geniculate nucleus (LGN) relays visual information from the retina to the primary visual cortex​. 2.​ What is population coding, and how is it used in neural representation? This involves representing sensory information through the combined activity of multiple neurons​. 3.​ Why is the ventral pathway referred to as the "what" pathway? This pathway processes object identity, including color and shape​. 4.​ Match each retinal ganglion cell type (parasol, midget, bistratified) to the appropriate LGN layer (magnocellular, parvocellular, koniocellular). Parasol RGCs → magnocellular layer Midget RGCs → parvocellular layer Bistratified RGCs → koniocellular layer​  5.​ What types of stimuli do neurons in the MT area respond to best? Neurons in the MT area respond best to motion stimuli​. 6.​ What are simple cells in the visual cortex, and how do they respond to specific orientations? Simple cells respond to specific orientations of bars of light. 7.​ How does a bar of light at a specific angle affect the firing rate of simple cells? A bar of light at a specific angle maximizes the firing rate of simple cells​. 8.​ What visual properties are processed by the magnocellular layers of the LGN? These layers process motion and flicker. 9.​ What visual properties are processed by the parvocellular layers of the LGN? These layers handle object properties like color and form. 10.​What visual properties are processed by the koniocellular layers of the LGN? These layers respond primarily to color information​. Chapter 4: Object Recognition 1.​ What function does the fusiform face area (FFA) serve in the brain? Facial recognition. 2.​ What condition results from damage to the FFA, and how does it affect perception? Can result in a condition called prosopagnosia or visual agnosia (face blindness). 3.​ What is the role of the parahippocampal place area in visual perception? Recognizing and processing places, scenes, and spatial layouts. 4.​ What deficits might result from damage to the PPA? Topographic Agnosia (Place Blindness): Inability to recognize or identify familiar places or scenes. Example: A person may not recognize their own home or a familiar route. Impairments in Navigation: Difficulty using landmarks or spatial layouts to navigate. Example: Getting lost even in well-known environments. Difficulty with Scene Perception: Problems perceiving or making sense of complex scenes. Example: Struggling to distinguish a park from a cityscape.  5.​ What is the figure-ground organization, and how does symmetry influence it? Definition: Figure-ground organization is the process by which the visual system separates an image into: 1.​ The figure: The object of focus. 2.​ The ground: The background or surroundings. Symmetry strongly influences figure-ground organization because symmetrical shapes are more likely to be perceived as the figure (object) rather than the background. 6.​ How do convex borders affect the perception of figure vs. ground? Convex borders are more likely to be perceived as part of the figure, enhancing object recognition, while concave borders blend into the ground and are less likely to be seen as separate objects. 7.​ What are two challenges the visual system faces in object recognition? Clutter, variable views, object variety SLIDE 1 8.​ List the Gestalt principles of perceptual grouping. Proximity: Nearness. Similarity: Shared features. Common Motion: Moving together. Symmetry: Balanced forms. Parallelism: Parallel features. Good Continuation: Smooth, connected patterns. 9.​ What is perceptual interpolation, and how does it help us perceive hidden edges? Perceptual interpolation fills in missing edges or surfaces, allowing us to perceive complete objects even when parts are obscured. 10.​How does this process allow us to see a complete object when part of it is obscured? This process uses contextual cues, such as visible edges and prior knowledge, to maintain a coherent and efficient perception of the visual world. 11.​Explain the results of Davenport and Potter’s (2004) study on consistent and inconsistent objects in scenes. Davenport and Potter (2004) found that contextual consistency between objects and scenes improves recognition. Objects and scenes that matched (e.g., a football player on a field) were identified more quickly and accurately than inconsistent pairings (e.g., a football player in a church). This demonstrates that context significantly influences visual perception, making recognition easier when objects and scenes align.