What are the processes involved in constructing a linear order from a set of relations between pairs of elements in the order? Subjects were presented with sets of digit pairs and instructed to form a single digit string on the basis of the order relations expressed by the pairs; for example, given 57, 19, 71, the correct response is 5719. Manipulations of presentation order revealed constructive processes of varying difficulty depending on whether a pair has zero, one, or two digits in common with the digits held in memory as an incomplete, constructed string. The least difficult processes arise when there is one common element. If the common element occurs at the end of the string in memory, construction is easier than when the new digit must be added to the beginning of the string. When a pair has no digits in common with the string in memory, constructing the correct string becomes substantially more difficult, especially when subsequent pairs having two digits in common require that a tentative order of digits held in memory be reorganized.

Subjects constructed four-term linear orders from three sentences expressing the relationships between adjacent elements in the order. Successful performance was more likely when the second sentence introduced only one element not mentioned in the first sentence rather than two new elements and when the second and third sentences introduced new elements as grammatical subjects rather than objects. Except for the latter result, previously proposed theories of reasoning processes primarily in three-term series problems, predict other differences that failed to appear. Apparently, in longer series, memory limitations favor conditions in which each sentence after the first presents a relationship between a new and an old element in linguistic forms that identify the new element.A number of recent studies have shown that when a subject is asked to learn or remember a set of sentences that describe a linear ordering, what is remembered is the ordering rather than the individual sentences (Barclay, 1973;Potts, 1972). For example, when presented with the sentences, "The bear is smarter than the hawk, the hawk is smarter than the wolf, and the wolf is smarter than the deer," subjects construct and retain the following linear order: bear, hawk, wolf, deer. The evidence for the foregoing hypothesis consists of two types of findings. Potts (1972) showed that subjects who had studied sentences such as those given above were faster and more accurate in judging the truth of sentences describing nonadjacent members of the order, e.g., "The bear is smarter than the wolf," which they had not seen before, than in judging comparable sentences describing adjacent members, e.g., "The bear is smarter than the hawk," which they had seen. Barclay (1973) showed that subjects who had learned a set of sentences derived. from a five-term linear ordering responded in a sentence memory test solely on the basis of whether the sentences were true of the the ordering as opposed to their actual presence on the learning list. The best explanation of these findings is to assume that subjects construct their own linear array and respond to test items on the basis of whether the item is true or false of the array.Although a great deal of effort and discussion has been devoted to discovering the exact nature of the subject's mental representation of the order (Barclay & Reid, 1974;Potts, 1974;Scholz & Potts, 1974), somewhat less attention has been given to the question of how the mental ordering is constructed, and very little research has been conducted to determine what variables influence these constructive processes. Barclay (1973) has shown that instructions to the subjects can influence to some extent whether or not the linear order is constructed. But in cases where it is clear that subjects are engaged in constructing a linear order, there remains the question of how the constructive process operates. More to the point, Potts (1972) found that overall performance was poorer for subjects who received as input a compound sentence in which the s...

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"The Global CRO Council (GCC) for Bioanalysis was formed in an effort to bring together many CRO leaders to openly discuss bioanalysis and the regulatory challenges unique to the outsourcing industry"

The present investigation was condueted to determine whether subjects could use categorical codes based on semantic memory information (gender of names) to make rapid decisions about the order of names in a linear series. Subjects were taught linear order problems in which 12 names (six male and six female) were either randomly ordered or blocked by sex. The results support a dual-process model which proposes that subjects use both categorical information (discrete linguistic codes) and serial position information when asked to make mental comparisons of arbitrarily ordered items. Furthermore, the data indicate that both the ordinal distance between the terms in the test pair (step size] and the serial position of the test terms in the linear order affect the reaction time to a particular test comparison.Recent studies of mental comparisons have eonsistently found that, when eomparing two items on a particular dimension (e.g., size, height, etc.), the more discrepant the two stimuli, the easier the comparison. This phenomenon is known as the distance effect (Potts, Banks, Kosslyn, Moyer, Riley, & Smith, 1978). Much of the research concerning the distance effeet has involved the retrieval and use of information in semantic memory. For example, digits (Moyer & Landauer, 1967), animal names (Moyer, 1973), and object names (Paivio, 1975) were used as stimuli in these studies. It is also possible to teach subjects an arbitrarily ordered sequence, test them on comparisons, and still obtain the distance effect. For example, Potts (1972) presented subjects with a paragraph that contained several sentences of the form, "The X was friendlier than the Y," where X and Y were animal names. After studying the paragraph, subjects were asked to make pairwise comparisons. As in previous studies, reaction time decreased as the distance between the items on the imposed scale increased.Many different models have been proposed to account for the distance effect. These models can be grouped into the following categories: analog models, discrete coding models, dual-process models, and serial position models. Each model makes certain assumptions This report is based on a thesis submitted in partial fulfillment of the requirements for the