Chapter 5 – Sensation and Perception

Chapter 5 – Sensation and Perception - Chapter 5...

This preview shows page 1 - 3 out of 5 pages.

Chapter 5 – Sensation and Perception Sensation – the stimulus-detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain Perception – active process of organizing the stimulus input and giving it meaning Sensory Processes Stimulus detection – absolute threshold designated as the lowest intensity at which a stimulus can be detected 50% of the time Signal detection theory – concerned with the factors that influence sensory judgments o Decision criterion – standard of how certain a person must be that a stimulus is present before they will say they detect it o Increased rewards for noticing stimuli often results in lower detection thresholds o Increased danger/punishment for noticing stimuli often raises detection threshold Difference threshold – smallest difference between two stimuli that can be perceived 50% of the time (just noticeable difference – jnd) o Weber’s Law – to perceive a difference between two stimuli, one must differ by a constant ratio Value for weights = 1/50, therefore if 50 lbs. is lifted, increased weight will only be detected at 51 lbs. Smaller fraction = higher sensitivity Doesn’t apply to extremely high or low stimulation intensities Sensory adaptation – the diminishing sensitivity to an unchanging stimulus o Perception of stimuli will decrease if constantly present The Sensory Systems Vision The Human Eye o Light enters eye through cornea (transparent protective structure) o Pupil – adjustable opening that dilates or constricts to control amount of light entering o Iris – controls the pupil o Lens – elastic structure that becomes thinner to focus on distant objects and thicker to focus on nearby objects Image flippedrrrrrrrrr and reversed onto retina Ability to see clearly depends on lens’ ability to focus image onto retina Myopia (nearsightedness) – lens focuses image in front of retina Hyperopia (farsightedness) – lens focuses image behind retina o Retina – multi-layered tissue at rear of eyeball Photoreceptors: Rods and Cones o Retina covered in light-sensitive receptor cells o Rods – black and white receptors Function best in dim light o Cones – color receptors Function best in bright light o In humans, rods are everywhere except fovea (direct center of retina) Cones decrease in concentration distant from the fovea o Rods and cones send message to brain via two additional layers of cells
Image of page 1

Subscribe to view the full document.

Bipolar cells have synaptic connections with rods and cones Bipolar cells synapse with ganglion cells, whose axons form into optic nerve o Cones in the fovea each have private line to a single bipolar cell (unlike others, which have many rods/cones for each bipolar cell)
Image of page 2
Image of page 3
  • Spring '09
  • ATKINSON
  • Psychology, Color blindness

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern