Poggendorf Lab• Visual Perception and Visual

Illusions• Relates to other vision labs, Stroop

and RPS– Prism goggle lab was an optical

illusion, different than a visual illusion (eye/mind distinction)

Two Different Views of Visual Perception and Psychology in

General

• Look for organizational principles

• Perception is an organized whole

• Whole (does not equal) Sum of Parts

Bottom Up: Structuralists Top Down: Gestaltists• Look for the “building blocks” of a given phenomenon

• The “building blocks” of perception are sensations

• Whole = Sum of Parts

The Gestaltists Used Illusions to Show that Perception was Organized

Subjective Contours The Zollner Illusion

The Necker Cube The Poggendorff Illusion

The length and width of these two tables is actually the same!

The black dots are phantom

Can you see the Dalmatian?

These Monsters are the same size…Illusion of converging lines toward the horizon

Mueller-Lyer Illusion: The lines are all the same length

Café Wall Illusion: The color and dis-alignment of the bricks causes the lines to look wavy.

They are actually parallel.

Align the “upper half” of a Poggendorff illusion line with bottom half so that there appears to

be one continuous line through the box

Deviation from the “actual” straight

line is the Dependent Variable-measured by points

Your Task:

The Width of the Box,The Angle of the Line, and Practice are the

Independent Variables

Width

Angle

Deviation

Some Results (from a previous class)

2.42.8

3.7

0

0.5

1

1.5

2

2.5

3

3.5

4

Err

or (

pts)

30 45 60

Degree of Entry

Effect of Angle

2.2

3.2 3.4

00.5

11.5

22.5

33.5

4

Err

or (

pts)

60cm

100c

m

140c

m

Width of Box

Effect of Box Size

And the ever present Practice Effect

Effects of Practice

0

2

4

6

8

10

12

Trial 1 Trial 2 Trial 3

Trial Number

Err

or (

pts)

In HOT PINK!