“Preferences and Demands of the White Rat for Food”, 1938 (; backlinks):
This paper is divided into 5 parts, each of which reports the results of experiments on some aspect of food preference.
§1 concerns spatial factors in feeding behavior. Experiments summarized here demonstrate that there are marked individual differences in right-left dominance, that size and position of food may obscure natural food preferences, that certain techniques may alter apparent preferences in several ways, and that equality of spatial advantage is the most favorable condition for expression of food preference.
§2 describes a revolving-cup technique and compares results obtained by its use with those found in research involving other techniques.
In §3 there is an evaluation of the ratio of eating to non-eating time as an index of demand for a given food. This ratio was quite variable and is thus considered unsatisfactory.
Rate of eating, a study of which comprises §4 of this research, is fast at first, and then slower and slower until satiation is reached. The amount of food needed to produce satiation varies with kind and quality of food. A quantitative goal can be determined experimentally for each kind of food. A goal gradient with negative acceleration is noted here.
§5 includes discussion of a hypothesis regarding the bodily mechanism of food demand and preference and description of an apparatus for automatically recording the eating rate.
…Spatial factors in the feeding behavior of rats
…8 rats showed marked individual differences in spatial behavior between the extremes of right and left dominance. The tendency of an animal to eat the test-food in a given position, right or left, frequently appears instead of preferential discrimination. Two attempts were made to control the factor of position.
The path of approach to the test-foods was moved bit by bit to the right or left.
The angular position of the pair of food-containers in relation to the line of approach was varied so as to advance one and withdraw the other.
Both methods gave the same result. It was possible to reduce, eliminate and even reverse the tendency of an animal to eat the food in a given right or left position. When the spatial advantage of both foods was the same, the conditions were most favorable for discovering the rat’s food preferences. The animal could not, however, be forced into making a choice. Preference is assumed to depend upon organic factors rather than upon the environmental arrangement of test-foods.