1850's to 1920's:

In James' time, the only method available to study attention was introspection. Very little progress was made in quantifying the study of attention, though it was considered a major field of intellectual inquiry by such diverse authors as Sigmund Freud, Walter Benjamin, and Max Nordau. For example, one major debate in this period was whether it was possible to attend to two things at once (split attention). Some thinkers felt that they were unable to do so, and other thinkers felt that they could. Without experiments, it was impossible to settle the debate.

1920's to 1950's:

From the 1920s to the 1950s, the field of attention was relatively inactive. The dominant psychological paradigm at the time was Behaviorism. This view was strongly opposed to anything cognitive, partially as a reaction to the endless debates of the introspectivists. Thus there were still no tools for quantitative measurements.

1950's to present:

In the 1950s, the cognitive revolution began, and psychologists renewed their interest in attention. Cherry and Broadbent, among others, performed experiments on dichotic listening. In a typical experiment, subjects would listen to two streams of words in different ears of a set of headphones, and selectively attend to one stream. After the task, the experimenter would ask the subjects questions about the content of the unattended stream.

During this period, the major debate was between early-selection models and late-selection models. In the early selection models, attention shuts down processing in the unattended ear before the mind can analyze its semantic content. In the late selection models, the content in both ears is analyzed semantically, but the words in the unattended ear cannot access consciousness. This debate has still not been resolved.

In the 1960s, Anne Treisman began developping the highly influential Feature integration theory (first published under this name in 1980 when it became famous in a paper with G. Gelade). According to this model, attention is responsible for binding different features into consciously experienced wholes. Although this model has received much criticism, it is still widely accepted or held up with modifications as in Jeremy Wolfe's visual search paradigm.

In the 1960s, Robert Wurtz at the NIH began recording eletrical signals from the brains of macaque monkeys who were trained to perform attentional tasks. These experiments showed for the first time that there was a direct neural correlate of a mental process (namely, enhanced firing in the superior colliculus).

In the 1990s, neuroscientists began using fMRI to image the brain in attentive tasks. The results of these experiments have shown a broad agreement with the psychophysical and monkey literature.