Psychology 2606

 We are clearly the most cognitively complex animals on this planet
 We can think about objects that are not present
 We can think about abstract ideas
 We use symbolic and syntactic language
 We plan and string events together

So, how is thought encoded in the brain?
 Monkeys, dots, motion and V5
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So, individual cortical neurons were detecting motion and making decisions
Hebb’s idea of the cell assembly
 The association cortex is key in thought
 Anything not primary is association (that is most of the cortex)
 Receives input from the thalamus, but from areas that themselves get input from primary sensory areas

 Our ability to deal with spatial stimuli may have helped us evolve ‘consciousness’
 That and the standing up and big heart thing
 We seem to have specialized sub systems to deal with different types of information
 Modules if you will

David R. Brodbeck 1
Andrea E. Pike 2
Cory Spracklin 1
Department of Psychology
1-Sir Wilfred Grenfell College, Memorial University of Newfoundland,
Corner Brook, NL
2Memorial University of Newfoundland, St. John’s, NL

 Cheng (1986) got the ball rolling
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Or the cocoa puff, as the case may be…
 Basically, he found that rats would use geometric information to locate food in a rectangular arena
 Most of their errors were to rotations of the originally baited location

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He then applied featural information
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 walls corners
The rats still made errors, though most of these were rotational errors
He concluded that the rats were responding to the geometry of the box.

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Tried the Cheng task with toddlers and adults
Disoriented the subjects
Using a cue
Toddlers are not unlike rats
Adults are different, seem to follow the cue
Same in Pike (2001)

 We decided to rotate the object
 A rectangle on a computer monitor
 Subjects (or participants, or whatever..) were shown a red dot on a black rectangle
 The rectangle was spun about the middle
 Dot faded
 Where was the dot?

Original Dot Location Reflection Error
31.0% +/- 2.77
18.2% +/- 3.43
Reflection Error
17.4% +/- 2.88
Rotational Error
33.4% +/- 3.94

Original Dot Location Reflection Error
37.2% +/- 3.58
11.6% +/- 3.38
Reflection Error
10.8% +/- 2.88
Rotational Error
40.4% +/- 3.62

 Well, it seems that whenever they can, people will use geometry in this task
 Even if there is a reliable cue
 What if we made geometry useless?
 A square

Original Dot Location Reflection Error
23.2% +/- 2.57
24.8% +/- 3.46
Reflection Error
23.4% +/- 2.99
Rotational Error
28.6% +/- 4.00

Original Dot Location Reflection Error
34.2% +/- 2.79
23.2% +/- 3.63
Reflection Error
28.0% +/- 3.01
Rotational Error
14.6% +/- 3.77

 Evidence of a feature independent geometric module
 People will use features, if forced
 Under certain circumstances
 Rotational errors disappear when geometry is useless
 Errors then become based on the feature

 Clear evidence (we think) of a feature independent, geometric module in human spatial processing
 Perhaps if we slowed the rotation we would find better performance, and fewer rotational errors in the cued condition
 (Rotation was titrated until we found errors reliably)

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Does Length : Width follow Weber’s Law?
 What if the dot was put closer to the centre of the stimulus?
 Touch screen
 Hmmm what about pigeons?

 It may be the case that input from this spatial module, or cell assemblies on top of cell assemblies comes together in associative areas
 These modules can be isolated WITHOUT wet neurophysiology
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So, ‘the dot is here’ could be considered a
‘thought’

 In the cortex there are columns, individual bunches of cells that go across layers of the cortex that seem to for circuits together
 Is this the unit of thought?
 Well, it might have something to do with it
 But still, we put all of our sensory and memorial thoughts together to form an experience

 So, how are all of these things put together into an experience?
 The Binding Problem
 This, and the engram may be the holy grails of neuroscience and psychology