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Geometric vs Featural Processing : Are They Lateralized in Humans ? . Stephanie E Tanninen and David R Brodbeck (@ dbrodbeck ) Department of Psychology, Algoma University, Sault Ste. Marie, ON, Canada. Introduction. Cheng (1986) got the ball rolling
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Geometric vsFeatural Processing: Are They Lateralized in Humans? Stephanie E Tanninen and David R Brodbeck (@dbrodbeck) Department of Psychology, Algoma University, Sault Ste. Marie, ON, Canada
Introduction • Cheng (1986) got the ball rolling • 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
Cheng (1986) • He then applied featural information • 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.
Hermer and Spelke (1994) • 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)
Brodbeck et al (2003) • We spun a rectangle with a fading red dot • Subjects were asked to say where the dot was after 8 sec of spinning • Subjects relied on geometry pretty much completely, until it became useless (when using a square)
Vallortigara et al 2004 • Trained chicks on the task • Covered one eye, or the other • Also tested both eyes uncovered • lateralized
We wondered • As we get similar results in humans and other animals • As Human spatial tasks are generally lateralized • Are results in the spinning rectangle task lateralized?
Method • Subjects had a white rectangle presented to them on a monitor • Presented binocularly, left field, right field • A red dot was in one of the corners • The dot faded • Where was the dot? • Using either a feature (yellow strip) or not
What We Expected • We figured they would follow the feature more in the right visual field condition (left field, right hemisphere = space, that sort of thing) • So, basically an interaction of viewing condition (left, binocular and right) and feature presence or absence
Results • The results did not differ depending on visual field • We also did not get the error pattern from Brodbeck et al (2003)
What does this all mean? • Well, the pattern of errors did not change depending on visual field which leads us to conclude, for the moment, that this task is not lateralized in humans • Makes some sense, we are not birds, we have a corpus callossum
Yeah but…. • We also did not find the pattern of errors we expected • This is likely a matter of the speed of the spinning rectangle • We used 90 rpm, Brodbeck et al used 480 • We found some suggestive sex differences, (males making more rotational errors) but we only had 5 men vs 17 women
Future directions • Try again making the task harder (our goal here was not to replicate so much as to look for a suggestion of lateralization) • When does a square become a rectangle? • Is that perhaps lateralized, or are there sex differences?
