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Paw Preference Handedness in humans comes in the form of being left handed, right handed and both handed (ambidextrous). Research has shown that the vast majority of people are right handed with only 8-15% left handed and a minority being ambidextrous. Brown rat displays an identical preference amongst the rat population for choice of paw as humans do for handedness. The December 2003 International Journal of Neuroscience published an article that related to testing lab rat's paw preference using a computerised food reaching test. The abstract for the test was as follows: We re-studied the distribution of paw preference in rats using a new computerized food-reaching test, which recorded the times and time intervals between the single right- and left-paw entries. Using the traditional food-reaching test, we found that of 144 rats, 72.7% were right-handed, 19.7% left-handed, and 7.6% mixed-handed. This population-level J-shaped right-hand preference did not fit a binomial chance distribution (25:25:50). Of right-handers, 99.5% first used their right paw and 0.5% left paw; of left-handers, 98.6% first used their left paw and 1.4% right paw. Of mixed-handers, 59% first used the right paw and 41% left paw for food reaching. The time interval between putting the rat into the test cage and the first right-paw entry was significantly shorter than the first left-paw entry in total sample. Males were faster than females (shorter time intervals between right- or left-paw entries). The distribution of the time intervals between right- or left-paw entries was inverse J-shaped, which exhibited a normal distribution after taking the logarithms of the time intervals. There was no significant difference between time intervals for the left-paw entries; time intervals for the right-paw entries were significantly shorter in males than females, accentuating the role of the left brain for sex differences in motor control. The results suggested that humans are not unique in population-level right-hand preference; our new method would be suitable for new developments in handedness research.
POPULATION-LEVEL RIGHT-PAW PREFERENCE IN RATS ASSESSED BY A NEW
COMPUTERIZED FOOD-REACHING TEST Using pieces of grilled chicken as a stimulating incentive, I was able to observe Sally and Rena's paw preference and see a pattern emerging in their choice. Rena appeared to be left handed while Sally didn't really display a firm preference for either. The following videos show how simple it is to conduct this experiment with the aid of a barred cage.
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