nvestigated the influence of vividness on learning. These early studies, for the most part, did not employ statistical analysis. Thus, the principal contribution of these studies was the identification of factors, which in some way and to some extent, influence learning. Without the benefit of statistical analysis, these early studies were not able to measure the degree to which a specific factor influenced learning.
The von Restorff studies reported in 1933, for the first time, relied heavily on statistical analysis to measure the impact of a specific factor on learning (Wallace, 1965, p. 410). The factor investigated in the von Restorff studies was the isolation factor (Wallace, 1965, p. 410). The findings of the von Restorff studies were summarized by Wallace (1965, p. 410) as follows: "Isolating an item against a crowded or homogeneous background facilitates the learning of that isolated item." Many subsequent studies through the mid 1960s both confirmed von Restorff's original findings, and expanded the knowledge of how the isolation effect works (Wallace, 1965, p. 411).
The studies investigating the isolation effect identified the following as the three major ways in which isolation may be manipulated: (1) performing an additional operation on one item within a list of items, such as making that item a different color from the others, or by circling the single item; (2) inserting one item of a different type within a list of otherwise similar items; and (3) through the structural organization of a list of items, which requires the use of an equal number of two different types of items within a single list, wherein the two types are massed with the exception of a single item which is situated in the center of a dissimilar mass of items (Wallace, 1965, p. 412).
One of the more significant of the findings of the studies conducted through the mid 1960s was that, while the use of an isolate within a list facilita...