Selby H. Evans

A brief statement of schema theory

Schema theory has recently been extended, coupled with suitable stimulus generating, procedures, and shown to have some predictive utility. A concise summary of extended schema theory is here presented, with provisional definitions of key terms and a statement of the basic suppositions. A distinction is made between the single schema condition and the mixed schema conditions; suppositions about schema learning are offered for both cases.

Schematic concept formation: Demonstration in a free sorting task

Presented with a set of patterns containing two schema-defined categories, Ss were asked to sort the patterns into two categories. No instructions about relevant attributes were given, and no feedback was provided. A significant number of Ss used the schema-defined categories in sorting.

Effects of knowledge of results on mixed schema discrimination

In a mixed schema task, Ss learned to distinguish among different schemata both with and without knowledge of results (KR). KR did not appear to assist schema learning. These results indicate that humans can discriminate higher order variables (schemata) without external assistance.

Utilizing intact and embedded headings as processing aids with nonnarrative text

Abstract This study examined the utility of intact (i.e., topic outline format) and embedded (i.e., appropriately positioned within the text) headings as processing aids with nonnarrative text. The argument was advanced that headings potentially provide useful cues for both input and output processing but that little empirical evidence exists to either support or refute this proposition. It was further argued that each of the prior studies reviewed were subject to one or more methodological criticisms which may attenuate the generality of the findings. The results of the present study indicated that no advantage accrued to students on the basis of training; however, limitations of this finding are discussed in terms of the amount of training provided and the time available to the students for integrating the new strategies with their existing techniques. The major result of this investigation was that students provided with text containing intact and embedded headings significantly outperformed students whose text did not contain these processing aids. The major benefits were observed at delayed testing; the text-with-headings students recalled approximately 11% more information at immediate testing and 44% more information at delayed testing than the text-without-headings students. Implications of these results and future research issues are discussed.

Schematic concept formation as a function of constraint redundancy and knowledge of results

The present study assessed the joint effects of schematic redundancy (Rc) and knowledge of results (KR) on performance of a modified oddity task requiring the assignment of stimuli to categories corresponding to three different schema families. A high level of Rc (70%) facilitated schematic concept formation (SCF); a low level of Rc (40%) prevented the occurrence of SCF, but didactic concept learning did occur at this level if KR was provided.

VARGUS 9: Computed stimuli for schema research

A method is presented for producing stimuli by sampling from a defined population in such a way that each stimulus may be regarded as a set of measurable deviations from a prototype. Procedures are described for the measurement and control of two population characteristics derived from information theory: stimulus channel capacity and redundancy. An interval scale measure is presented for describing individual stimuli with respect to conformity to the prototype.

Schema discrimination as a function of training

With knowledge of results Ss learned to distinguish between the presence and the absence of a schema and to distinguish between different schemata. Since a schema may be regarded as a statistical concept, the results also show that humans readily learn statistical concepts.

Schema learning without a prototype

In a reproduction task, Ss benefitted more from training with patterns having a common schema than with random patterns, even though Ss saw no prototype. This schema learning occurred with knowledge of results.

Free sorting with stimuli clustered in a multidlmensional attribute space

An experiment was conducted to determine whether Ss leam, without knowledge of results or prior familiarization with the prototypes, to sort histoform stimuli generated by three probablistic rules into categories consistent with these mies. Seven Ss were asked to sort 30 stimuli (10 from each schema population) on each trial. No constraints were placed on the number of categories to be used. A statistic was developed to measure consistency between schema-defined categories and subjeet-defined categories. Four of the seven Ss met the leaming criterion, and demonstrated increasing consistency with the schema-defined categories across trials. In general, more categories than necessary were used to classify the stimuli correctly. The results raise several questions about classification strategies used by Ss in perceptual learning tasks with stimuli generated by probabilistic rules, and indicate the need for further research conceming the variables that influence perceptual category formation.

Recovery of function from septal damage and the growth of sympathohippocampal fibers

After septohippocampal damage in the rat, a growth of fibers of sympathetic origin is observed in the hippocampus. The time course of this growth parallels the changes in behavior seen after septal lesions. This study determined quantitatively which pattern of behavioral changes was most closely associated with the growth of sympathetic fibers. We found two patterns of behavioral change associated with the growing fibers. One pattern was of “recovery” behaviors, whereas the other was of “deficit” behaviors. The recovery behaviors included tactile reactivity and open-field activity. The deficit behaviors included shock and heat reactivity. In addition, we argue that the fluorescence intensity measure of sympathetic fibers that relates to neurotransmitter content is most appropriate to use in future studies of behavior, because this measure was consistently well correlated with behavioral changes.