Jerome Bruner (Dept. of Social Relations, Harvard, from 1946): Known as one of the architects of the cognitive revolution (though he has been far more influential in the fields of education and cultural and social psychology - inspired discovery learning in the 60s, MACOS and cross-cultural studies).
Bruner's early work in perception denied that external stimulus is the determining factor; emphasised contribution of internal mental states, partly determined by social factors.
Eg. (Bruner and Cecile Goodman in 1947) found that children's judgement of the size of coins varied with their value: the size of lower-valued coins was underestimated while that of higher-valued coins was overestimated. (Contradicted the general psychophysical law of central tendency - error in direction of mean.) Further, the overestimations were higher in poorer children.
Bruner and Postman: Studied ability of subjects to read words flashed through a tachitoscope. Time required for reading varied with meaning of word - factors like closeness with strongly-held values. i.e. semantic significance was affecting processes prior to the actual recognition of the word. Eg2 - anomalous cards (eg. red 10 of clubs) were recognised faster when anomalies were expected - before that they were mis-perceived (i.e. as 10 of diamonds) (Thomas Kuhn was a Harvard Fellow at this time and these studies influenced his idea that scientists fail to see certain phenomena till a new paradigm changes their expectations.)
Later Bruner did more direct studies of thinking (A Study of Thinking, 1956): Array of cards with geometrical patterns in systematic combinations. Subject had to guess a category rule by selecting cards, each time being told if they were exemplars or non-exemplars. Common strategy was to find one positive instance of the category and then systematically pick cards that varied in one attribute. These experiments on category reasoning led to Peter Wason and Philip Johnson Laird's 1970s studies on confirmation bias in category reasoning tasks and Eleanor Rosch's study of natural categories (which showed that defining rules as found in the artificially constrained categories did not exist). (More in Semester 2 - Concepts and Categories)