Psychology Chapter 3 Flashcards

Questions and Answers

What is lateral inhibition and why was it first studied in the Limulus?

Lateral inhibition is the capacity of an excited neuron to reduce the activity of its neighbors. It was first studied in the Limulus because it illustrates how retinal inhibition works.

Explain the Hermann Grid.

The Hermann Grid creates an illusion due to lateral inhibition, where neurons at the intersections receive more inhibition, making them appear darker compared to the corridors.

Explain Mach Bands.

Mach Bands are visual effects where lighter bands appear around shadows due to differential inhibitions from light and dark areas, providing sharper boundaries.

Explain simultaneous contrast.

Simultaneous contrast occurs when gray boxes surrounded by light appear different from those surrounded by darkness due to varying levels of inhibition. Signup and view all the answers

What is White's Illusion?

White's Illusion refers to the perception that an area's appearance is influenced by its surroundings, challenging the explanation of lateral inhibition. Signup and view all the answers

What do the receptive fields look like in the optic nerve (ganglion cells) and LGN?

Receptive fields trigger firing in a particular region of sensory space, with 90% of information from the optic nerve sent to the LGN, showing little change from the retina. Signup and view all the answers

What is the difference between excitatory-center, inhibitory-surround receptive fields and inhibitory-center, excitatory-surround receptive fields?

Excitatory-center, inhibitory-surround receptive fields exhibit more firing, while inhibitory-center, excitatory-surround receptive fields show less firing. Signup and view all the answers

Explain center-surround antagonism.

Center-surround antagonism occurs as light fills more of the receptive field, causing an initial increase in response followed by a decrease. Signup and view all the answers

Describe the nature of simple cortical cells, complex cortical cells, and end-stopped cortical cells, and the stimuli they are responsive to.

Simple cortical cells respond best to light in a line of particular orientation, complex cortical cells respond to lines moving in specific directions, and end-stopped cortical cells respond to moving lines of a certain length or moving corners. Signup and view all the answers

Study Notes

Lateral Inhibition

Lateral inhibition refers to the capacity of an excited neuron to inhibit its neighboring neurons, enhancing contrast in visual perception.
This phenomenon was first examined in the Limulus (horseshoe crab) due to its simple visual system, allowing for clearer observations of neuronal interactions.

Hermann Grid

The Hermann Grid illusion occurs because neurons at grid intersections experience heightened lateral inhibition compared to those along corridors.
This illusion disappears when observed directly, as the fovea’s smaller receptive fields reduce the impact of lateral inhibition.

Mach Bands

Mach Bands create an illusion of enhanced brightness at the edges of a shadow, providing sharper visual boundaries.
Lighter areas adjacent to darker regions receive stronger lateral inhibition, making them appear even brighter than uniformly lit areas.

Simultaneous Contrast

In simultaneous contrast, gray boxes surrounded by lighter backgrounds receive increased inhibition, making them appear darker.
Conversely, when surrounded by darker areas, the inhibition effect is diminished, altering perceived brightness.

White's Illusion

White's Illusion demonstrates that lateral inhibition alone cannot explain certain visual effects due to the influence of "belongingness," where an area's appearance is affected by its perceived relationship to surrounding elements.

Receptive Fields in the Optic Nerve and LGN

Receptive fields correspond to specific sensory regions that trigger neuronal firing when stimulated.
Approximately 90% of the information from the optic nerve is transmitted to the LGN with minimal alteration from the retina.

Receptive Field Types

Excitatory-center, inhibitory-surround receptive fields result in increased neuronal firing when the center is stimulated.
Conversely, inhibitory-center, excitatory-surround receptive fields show reduced firing in response to center activation.

Center-Surround Antagonism

Center-surround antagonism describes how neuronal response initially increases with light exposure in the receptive field but eventually diminishes as more of the field is illuminated.

Cortical Cells Responses

Simple cortical cells are primarily responsive to light stimuli arranged in specific orientations.
Complex cortical cells respond optimally to lines that move in particular directions.
End-stopped cortical cells react to lines of a specific length and to moving corners or edges.

Description

Test your knowledge on Chapter 3 of Psychology with these flashcards. Explore the concept of lateral inhibition and its significance in neurobiology, particularly its initial studies in the Limulus. Perfect for quick revision and deeper understanding.