4.1—sensation and perception Flashcards Preview

🚫 PSY100H1: Introduction to Psychology (Winter 2016) with J. Vervaeke > 4.1—sensation and perception > Flashcards

Flashcards in 4.1—sensation and perception Deck (20):
1

4.1 Learning Objectives

2

4.1 Focus Questions

3

Sensation

the process of detecting external events by sense organs and turning those stimuli into neural signals.

4

Perception

involves attending to, organizing, and interpreting stimuli that we sense.

5

Transduction

  • transduction: when specialized receptors transform the physical energy of the outside world into neural impulses.
  • raw sensations detected by the sensory organs are turned into information that the brain can process through transfuction.
  • this ultimately gives rise to our internal representation of the world.
  • all of our senses use the same mechanism for transmitting information in the brain: the action potential.
  • in order to separate different sensory signals from one another so that we can experience distinct sensations, the brain sends signals from different sensory organs to different parts of the brain.

A image thumb
6

Doctrine of Specific Nerve Energies

  • doctrine of specific nerve energies: first proposed in 1826 by the German physiologist Johannes Müller; the idea that different senses are separated in the brain.
  • these pathways are built through experience.

7

Sensory Adaptation

  • sensory adaptation: the reduction of activity in sensory receptors with repeated exposure to a stimulus. 
  • unchanging stimuli elicit less activity in the nervous system, and are percieved as being less intense over time.
  • e.g. directors changing camera angles so that your brain can't adapt and will keep hold of your attention.

8

Psychophysics

  • psychophysics: the field of study that explores how physical energy such as light and sound and their intensity relate to psychological experience 
  • e.g. how much perfume would need to be spilled in a three-you apartment for you to detect the odour?

9

Absolute Threshold

  • absolute threshold: the minimum amount of energy or quantity of a stimulus required for it to be reliably detected at least 50% of the time it is presented.
  • this varies among individuals (and species) and across the life span.

A image thumb
10

Difference Treshold

  • difference threshold: the smallest difference between stimuli that can be reliably detected at least 50% of the time. 
  • e.g. adding one pinch of salt to fries with no salt will create a different taste from adding one pinch of salt to fries that already have four pinches of salt.

11

Stimulus Threshold Limitations

  • the study of stimulus thresholds has its limitations.
  • whether someone perceives a stimulus is determined by self-report—an individual reporting that she either did or did not detect a stimulus.
  • not all people are equally willing to say they sensed a weak stimulus; some will wait until they're 100% certain.
  • e.g. real-world implications: radiologist trying to detect tumours in a set of images.
    • if there are differences in the absolute threshold of different radiologists, then one might miss tumours that the other would have detected.

12

Signal Detection Theory

  • signal detection theory: whether a stimulus is perceived depends on both sensory experience and judgment made by the subject.
  • sensory process: signal detection experiment conducted in the laboratory, the experimenter presents either a faint stim- ulus or no stimulus at all.
  • decision process: subject is asked to report whehter or not a stimulus was actually presented.
  • hit: correct that you heard a sound.
  • correct rejection: correct that you didn't hear a sound.
  • false alarm: think you heard something that's not there.
  • miss: fail to detect that a stimulus was presented.
  • by analyzing how often a person’s responses fall into each of these four categories, psychologists can accurately measure the sensitivity of that person’s sensory systems.

  • motivational changes are likely to affect your decision process, changing your sensitivity. (i.e. you're more likely to hear a bear growl or twig snap on your own at night in the woods than with friends hiking.)

A image thumb
13

Subliminal Messaging

  • we can perceive subliminal stimuli under strict laboratory conditions.
  • subliminal perception can occur, and it can produce small effects in the nervous system.
  • claims that subliminal perception can influence behaviours may be inaccurate.
  • e.g. Greenwald study
    • even if changes were to occur after a subject heard subliminal tapes, these effects may be due to the participants' expectations.
    • people were given two sets of tapes (e.g. a memory cassette with memory label, and a memory cassette with a self-esteem label).
    • participants experienced improvement based on the labels, and not what they actually heard.
  • subliminal messages are unlikely to create motivations that hadn't previously existed.
  • therefore, it's definitely not a form of mind control.

14

Gestalt Psychology

  • Gestalt psychology: "the whole is greater than the sum of its parts."
  • figure-ground principle: objects or "figures" in our environment tend to stand out against a background.
  • proximity; we tend to treat two or more objects that are close in proximity to each other as a group.
  • similarity; experienced by viewing groups of people in uniform.
  • continuity: "good continuation"; lines and other objects tend to be continuous, rather than abruptly changing direction.
  • closure: the tendency to fill in gaps to completely a whole object.
  • Gestalt concepts are not simply a colelction of isolated examples; they demonstrate how we create our own organized perceptions out of the different sensory inputs that we experience.

A image thumb
15

Phonetic Reversal

  • in 1985, two teens committed suicide (one lived), claiming their actions were influeced by "subliminal messages" found in the heavy metal music by Judas Priest.
  • the family sued the band, claiming that when played backwards, the song "Better by You, Better Than Me" contained the phrase "do it."
  • most examples of backward messages are due to phonetic reversal: where a word pronounced backwards sounds like another word.
  • after this, John Vokey and Don Read (in 1985) conducted experiments about backwards messages.
    • when asked to make judgments about the con- tent of the backward messages, participants' performance fell to chance levels.

    • they were unable to distinguish between nursery rhymes, Christian, satanic, pornographic, or adver- tising messages (19.1% correct, where chance performance is 20%) 

16

Top-Down Processing

  • top-down processing: when our perceptions are influenced by our expectations or by our prior knowledge.
  • in backward messages experiments, participants use top-down processing to perceive specific phrases.  

17

Bottom-Up Processing

  • bottom-up processing occurs: when we perceive individual bits of sensory information (e.g. sounds) and use them to construct a more complex perception (e.g. a message). 

18

Divided Attention

paying attention to more than one stimulus or task at the same time.

19

Selective Attention

focusing on one particular event or task.

20

Inattentional Blindness

  • inattentional blindness: a failure to notice clearly visible events or objects because attention is directed elsewhere.
  • accounts for many common phenomena; for example, people who witness automobile accidents or criminal behaviour may offer faulty or incomplete testimony  

Decks in 🚫 PSY100H1: Introduction to Psychology (Winter 2016) with J. Vervaeke Class (50):