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Influences on Perception

Module 2.1a

Do You See The DUCK?

Or do you see a RABBIT?

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Is it a Frog?

Or a Horse?

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Sensation vs. Perception

  • Sensation – to construct the outside world inside our heads we must detect physical energy from the environment and then encode it as neural signals.
    • Bottom-up processing—Data-driven where sensory information travels from receptors to the brain.
    • assembling a jig-saw puzzle without the picture
  • Perception - The process of integrating, organizing, and interpreting sensory information
    • Top-down processing— Draw upon our knowledge, experiences & expectations to arrive at meaning. Also called conceptually driven processing.
    • using the picture to assemble the jig-saw puzzle
  • Sensation and Perception blend into one continuous process, progressing upward from specialized detector cells and downward from our assumptions.

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Top-Down vs.

Bottom-Up Processing

Why is it you can navigate your dark bedroom in the middle of the night without seeing?

- Your prior experiences & expectations tell you what to avoid. (Top-Down Process)

What would happen if you were visiting someone’s house you don’t know well?

- You would have NO prior experiences & expectations to tell you what to avoid. Reliant only on your senses. (Bottom-Up Process)

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Selective Attention

  • Focusing conscious awareness on a particular stimulus to the exclusion of others
  • The ability to focus on one thing at a time
  • Allows a person to function in a world filled with many stimuli/distractions
  • People with ADHD have trouble doing this.

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Cocktail Party Effect

  • Demonstrates selective attention & dual processing
  • If talking to one person in a crowded noisy room you will still notice if someone says your name.
  • This demonstrates that even though you weren’t paying attention to a conversation across the room your brain was unconsciously monitoring (dual or parallel processing) your sensory info about the room and alerting your consciousness when there was something you needed to pay attention to.

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Selective Attention: An Example

  • View this updated version of Neisser’s Selective Attention Test basketball video clip below. Count the number of passes made by the girls in white. (click HERE to start)

Did you notice the lady walk across the room with the umbrella? No! You were too busy watching & counting the passes. Try this: https://www.youtube.com/watch?v=IGQmdoK_ZfY

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Inattentive Blindness

  • We are only able to pay attention to a tiny sliver of visual stimuli. Things outside our attention we are blind to
  • Caused by our amazing focus on just some parts of the environment.
  • Change Blindness – Failure to notice changes in the environment…sometimes obvious ones. - Watch these Person Swaps
  • Choice Blindness – Not noticing when your preferred choice has changed –Face Swap
  • Choice Blindness Explained

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Multitasking

  • Are we good at Multitasking? NO!
  • Try to do the following activity? How well could you attend to the multiple stimuli at once?
  • David Copperfield Magic Test
  • The Stroop Effect
  • NY Times Distracted Driving Simulator

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Perceptual Sets

  • Example:
    • If I have just said something that had a punch line, I’ve just told a _________
    • If someone is completely out of money, they might say “I’m _________”
    •  Wherever there is fire there usually is ____________
    • If I’m wet to the bone you’d say I’m ____________
    • The sound a frog makes is____________
    • We call the white of an egg the _________

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  • Top-Down Process that influences how we perceive things.
  • It is a method of PRIMING your brain to think a certain way.
  • Our expectations influence how we think and therefore perceive things.
  • Perceptual Sets influence how we understand information coming in from our senses.

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Perceptual Set

The influence of prior assumptions and expectations on perceptual interpretations

Bushes or Assassins of JFK?

Shadow or Sasquatch?

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Perceptual Set

What do you see in the center picture?

Half the Class View What’s Under the RED Square.

Other Half of the Class View What’s Under the YELLOW Square

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Perceptual Set

What do you see in the center picture?

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Perceptual Set

What do you see in the center picture?

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Perceptual Set

What do you see in the center picture?

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Perceptual Set

What do you see in the center picture?

  • What you see depends on what you looked at first.
  • You are primed to create a perceptual set of what to look for.

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Schemas

  • Mental representations of how things should be that influence our perceptions of people, memories and places.
  • Concepts or mental frameworks that organize and interpret information

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  • Imagine a DOG playing in the park.
    • What kind of dog did you imagine?
      • Probably one you’ve owned

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  • Imagine a dog attacks you at the park.
    • What kind of dog did you imagine?
      • Probably one you have heard is vicious.

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Schemas can Change as We Age

Children’s drawings reflect their schemas of reality, as well as their abilities to represent what they see. This drawing by 4-year-old Anna illustrates that the face has far greater importance than the body in young children’s schemas of essential human characteristics.

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Face Schemas

  • Which is the real Barack Obama?
  • We don’t have a schema for upside down faces.
  • As it switches you’ll find out the mouth and eyes have been changed.

Here is another one to view:

The Thatcher Illusion

Or Here to view it online

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HOLLOW MASK ILLUSION

  • How does our schema for faces help create this illusion?

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Click HERE to view it online

  • Your only experience is with noses that stick outward so when there is no clue to depth, your brain assumes the nose in the mask is sticking outward because that is the most logical perception based on your experiences.

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Context Effects

  • How you perceive something depends on the setting or environment you’re in.
  • You may perceive something one way and later in a different environment or context perceive it in an entirely new way.

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Context Effects

  • How you perceive something depends on the setting or environment you’re in.
  • You may perceive something one way and later in a different environment or context perceive it in an entirely new way.

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Context Effects

  • How you perceive something depends on the setting or environment you’re in.
  • You may perceive something one way and later in a different environment or context perceive it in an entirely new way.

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Context Effects

The magician’s cabinet:

  • Is the box in the far left frame lying on the floor or hanging from the ceiling?
  • What about the one on the far right?
  • In each case, the context defined by the inquisitive rabbits guides our perceptions.

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Context Effect Illusions

An object’s background can change and make us perceive things that are not really present.

Click on the video clip below. Are the lines slanted or straight?

The Café Wall Illusion Download

Online Version

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Spiral Square Case

Are these squares bent? The curves of the spiral in the background make the square seem bent. Ground has a role in how we perceive the figure.

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Context - Culture

  • Culture can also influence how we perceive information.
  • Nativist Position – people throughout the world view the world the same way because they share the same biological perceptual rules.
  • Empiricist Position – People actively construct their perceptions by drawing on their prior learning and cultural experiences.

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What is above the woman’s head?

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  • In one study, nearly all the East Africans who were questioned said the woman was balancing a metal box or can on her head and that the family was sitting under a tree.
  • Westerners, for whom corners and boxlike architecture are more common, were more likely to perceive the family as being indoors, with the woman sitting under a window.

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�Carpentered-World Hypothesis – People living in urban and industrialized environments where there are more right angles and straight lines will be more susceptible to the Muller-Lyer Illusion than people in non-carpentered natural environments. �

  • Top horizontal line looks longer because it also looks farther away
  • Inward pointing arrows signify that the horizontal line is closest to you
  • Outward pointing arrows signify the line is farther away

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Müller-Lyer Illusion

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�Carpentered-World Hypothesis – People living in urban and industrialized environments where there are more right angles and straight lines will be more susceptible to the Muller-Lyer Illusion than people in non-carpentered natural environments. �

  • Top horizontal line looks longer because it also looks farther away
  • Inward pointing arrows signify that the horizontal line is closest to you
  • Outward pointing arrows signify the line is farther away

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Müller-Lyer Illusion

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�Carpentered-World Hypothesis – People living in urban and industrialized environments where there are more right angles and straight lines will be more susceptible to the Muller-Lyer Illusion than people in non-carpentered natural environments. �

  • Top horizontal line looks longer because it also looks farther away
  • Inward pointing arrows signify that the horizontal line is closest to you
  • Outward pointing arrows signify the line is farther away

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Müller-Lyer Illusion

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Müller-Lyer Illusion�Which Line Appears Longer?

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Müller-Lyer Illusion

Most people think segment AB equals BC. In reality AB is much longer than BC.

See How this works HERE!

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Müller-Lyer Illusion

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Müller-Lyer Illusion

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Müller-Lyer Illusion

Click below to view a video of how this works:

Muller-Lyer Illusion Explanation

Which position best explains this illusion?

Nativist or Empiricist?

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Emotion & Motivation

  • How we perceive the world is influenced by our current emotional state and whether we are motivated to notice details.
  • Examples:
    • If you’re angry at a person, you perceive their normally neutral behavior as offensive or done on purpose to make you mad.
    • If you like a person, you’re not motivated to look for behaviors that they do that are annoying and likely don’t notice their annoying habits.