Psychophysical studies of visual object recognition Neurobiology - - PowerPoint PPT Presentation

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Psychophysical studies of visual object recognition Neurobiology - - PowerPoint PPT Presentation

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Psychophysical studies of visual object recognition Neurobiology 230. Harvard College/GSAS 78454 October 2, 2017 Jiye Kim What is psychophysics? Psychophysics is the study of the link between stimulus and perception and it quantitatively

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Psychophysical studies of visual

  • bject recognition

Neurobiology 230. Harvard College/GSAS 78454 October 2, 2017 Jiye Kim

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What is psychophysics?

Psychophysics is the study of the link between stimulus and perception and it quantitatively investigates the relationship between physical stimuli and the perception/ sensation/behavior they produce.

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Example psychophysical experiment

+ ? + ? Is the object an animate or inanimate object?

Yes! No!

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What do typical experiments measure?

Reaction time: The time taken by subjects to perform a task or

make a judgment. Reaction time can give an indication (or at least the upper bound) or how long the necessary psychological (and neural) processes take.

Performance: The accuracy of performing a task. Performance is

  • ften inversely related to reaction time.

Threshold: Stimuli can be varied (e.g., presentation duration) to

determine the threshold for detection or discrimination.

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Gestalt laws

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Law of closure Law of similarity Law of proximity Law of symmetry Law of continuity Law of common fate

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Law of closure

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We perceive objects such as shapes, letters, pictures, etc., as being whole when they are not complete. Specifically, when parts of a whole picture are missing, our perception fills in the visual gap.

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Law of similarity

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We group similar elements into collective entities or totalities. This similarity might depend on relationships of form, color, size, or brightness

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Law of proximity

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We group objects that are proximate to each other (either spatially or temporally) tend to be grouped together.

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Law of symmetry

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[ ] { } [ ] { }

We group elements that are symmetrical to each other tend to be perceived as a unified group.

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Law of continuity

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We perceive points that are connected by straight or curving lines are seen in a way that follows the smoothest path.

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Law of common fate

We perceive elements with the same moving direction as a collective unit.

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Hollistic process of face perception

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Part-whole effect Inversion effect Composite face effect

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Parts vs wholes effect in face perception

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Tanaka & Farah (1993)

Faces Houses Parts Whole

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Parts vs wholes effect in face perception

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Tanaka & Farah (1993)

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Part-whole illusion

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McKone et al (2013)

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Part-whole illusion

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McKone et al (2013)

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Inversion effect

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Inverted Upright

McKone et al (2013)

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Composite face effect

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A B

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Composite face effect

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Properties of object recognition

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Invariant object recognition Speed of visual recognition Recognition from minimal features The value of experience Invariant object recognition Speed of visual recognition Recognition from minimal features The value of experience

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Invariant recognition

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x

A A A A A A A

Scale/size tolerance

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Size invariance in visual object priming

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1st block 2nd block

same exemplar same size same exemplar different size different exemplar same size different exemplar different size

Biederman & Cooper (1992)

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Size invariance in visual object priming

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Biederman & Cooper (1992) perceptual priming effect

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Position invariance in visual object priming

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Biederman & Cooper (1991)

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Position invariance in visual object priming

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Biederman & Cooper (1991)

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Properties of object recognition

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Invariant object recognition Speed of visual recognition Recognition from minimal features The value of experience

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Speed of visual recognition

Irving Biederman

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RSVP (Rapid Serial Visual Presentation)

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Probing the timing of the visual system

Fize et al. (2005)

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Go- no go animal categorization task

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Properties of object recognition

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Invariant object recognition Speed of visual recognition Recognition from minimal features The value of experience

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Object recognition from minimal features

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Shimon et al (2016)

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MIRCs: MInimal Recognizable Configurations

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Shimon et al (2016)

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MIRCs: MInimal Recognizable Configurations

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Shimon et al (2016)

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Diagnostic features at the part-level

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Biederman (1987) Non- recoverable Recoverable Original

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Properties of object recognition

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Invariant object recognition Speed of visual recognition Recognition from minimal features The value of experience

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Visual recognition depends on experience

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Waterfall illusion

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http://www.michaelbach.de/ot/mot-adapt/index.html