“P300” and memory: Individual differences in the von Restorff effect

Event-related brain potentials (ERPs) were elicited by words in a free recall paradigm that included a novel item. The P300 component of the ERP is elicited by novel, task-relevant events, and we tested the hypothesis that P300 is a manifestation of the cognitive processing invoked during “context updating.” If the degree to which current representations in working memory need revision is related to P300 amplitude, then the P300 elicited by a given item should be related to the ability to recall that item on a subsequent test. Forty lists were presented to 12 subjects in each of two sessions. The lists were 15 words long, and 1 word, in position 6 through 10, was “isolated” by changing its size. Most subjects recalled these isolated words more often than other words in the same positions (von Restorff effect), and these words also elicited larger P300s than other words. Analysis of variance on the component scores from a principal components analysis revealed that words recalled had a larger amplitude P300 (on initial presentation) than words not recalled. Striking individual differences emerged, and there were strong relationships between the von Restorff effect, overall recall performance, mnemonic strategies, and the association between components of the ERP and recall performance. The overall recall performance of subjects who reported simple (rote) mnemonic strategies was low, but they showed a high von Restorff effect. For these subjects the amplitude of the P300 elicited by words during initial presentation predicted later recall. In contrast, subjects who reported complex mnemonic strategies remembered a high percentage of words and did not show a von Restorff effect. For these subjects P300 did not predict later recall, although a later “slow wave” component of the ERP did. The initial response to isolated items was the same for all subjects (a large P300), and all subjects recognized the isolates faster than other words in a recognition test given at the end of each session. The subjects in whom P300 did not predict recall reported mnemonic strategies that involved organizing the material. These strategies continue long after the time period reflected by P300 (600 msec). Because they were so effective they may have overshadowed the relationship between P300 and recall, which is based on the initial encoding of an event. Our interpretations were further confirmed and clarified from data obtained in a final grand recall and in the recognition test.     

A model of fixed activation time scheduling

A model for the fixed activation time scheduling of events is presented. Activation time is defined as the time needed for an event to regain dominance in the stream of events measured from the point in time at which it lost dominance. The fixed activation time scheduling rule states that some event must be ongoing at all times, that an ongoing event will continue until interrupted by another event, that every event has a predetermined activation time and that fulfilling the activation time requirement is the necessary and sufficient condition for an event to interrupt an ongoing event. The last condition sets this rule apart from those employed in quequeing theory since it does not allow events to be completed or queues to form. Derivations from the model concerning the dynamic organization of the stream of events, written in terms of the frequency and duration of events and the transitions between pairs of events, are given. Special attention is paid to issues that arise in deciding on the coding of events. It is suggested that the fixed activation time scheduling rule will apply to a wide variety of settings, environmental and behavioral, and this is illustrated by a detailed application of the model to observations on the stream of free behavior.     

The cognitive representation of persons and groups and its effect on recall and recognition memory

A conceptualization of the manner in which trait and behavioral information is organized in memory is proposed and applied in predicting both the recall and recognition of information about persons and groups. Three information presentation conditions were considered: (1) Subjects are told to form an impression of a target (person or group) on the basis of the target's behaviors, and are given a trait-based concept of what the target is like before learning about these behaviors. (2) Subjects are told to form an impression of the target, but a general traitbased concept of the target is not induced until after they learn about the target's behaviors. (3) Subjects receive information about the target's behaviors with instructions to remember the information, and only subsequently are told to form an impression and are given more general information about the target's traits. The proposed model accounted for between-condition differences in both the recall and recognition of behaviors that were consistent and inconsistent with a general trait-based concept of the target, and for contingencies of these differences on whether the target was a single person or a group.     

Predicting turnover intentions and turnover behavior: A multivariate analysis

This study assesses the relative influence of personal, attitudinal, and behavioral variables on behavioral intentions and voluntary turnover among nonsupervisory plant workers. Results show that personal variables have little direct effect on turnover; rather, their influence on turnover is channeled through their effects on behavioral intentions. Felt stress, organizational commitment, and behavioral intentions are found to be the strongest predictors of voluntary job termination. Weak support is found for absenteeism as a precursor of eventual turnover.     

Influence of occupational information giving on cognitive complexity in decided versus undecided students

Some research in the area of vocational counseling has focused on information-processing variables of subjects, such as the cognitive complexity-simplicity dimension. Because much vocational counseling consists of giving occupational information to the client, researchers have investigated the effect of information giving on the processing styles of subjects. Bodden and James (Journal of Counseling Psychology, 23, 280–282, 1976) found that giving occupational information to subjects caused them to become more cognitively restricted; they concluded that the practice of giving occupational information in counseling should be reexamined. The present study attempts to replicate that work while additionally controlling for the decided/undecided status of the subjects. Ninety-three subjects were administered the Career Decision Scale and the Cognitive Differentiation Grid at pretest. Subjects were then randomly assigned to the experimental-information condition or the control-no-information condition and were tested 48 hr later on the Cognitive Differentiation Grid. No significant differences were found between decideds and undecideds as a result of vocational information that they were given, and the results failed to replicate the Bodden and James (1976) findings. Implications of the results are discussed and further necessary research is specified.     

A hierarchy of information sources for inferring emotional reactions

The ability of children and adults to infer emotional reactions from different sources of information was investigated. Preschoolers (mean age, 4–9), second graders (mean age, 4–9), and college students were asked to infer emotional reactions from verbally presented stories in which sources of information occurred either singly, in conflict, or in congruence. The sources investigated were situational (the protagonist's social or physical situation), normative (the dispositions of a group to which the protagonist belongs), and personal (the dispositions of the protagonist in particular). Subjects indicated the protagonist's emotional reaction to an event in the story by choosing one of three facial expressions, representing happy, upset, and afraid. A hierarchy of sources for making emotional inferences was found at all three grade levels: personal information was preferred over normative information, and both were dominant over situational information. The relevance of present methods and findings to the study of the development of “empathy” is discussed.     

Developmental differences in cognitive scanning and encoding of visual information

Report accuracy of horizontally arranged letter sequences was measured for second-grade children and adults using a tachistoscopic single report procedure. Results indicated age differences in both the amount of information encoded out of visual sensory store and in the magnitude of left-right visual field differences. However, large age differences in amount of encoded information were also present under conditions which served to reduce left-right visual-field asymmetries in report accuracy. These findings are discussed in terms of their implications for using a left-to-right cognitive trace scanning explanation to account for age differences in encoding efficiency.     

The effect of context on the structure of categories

Three experiments examined the effect of context on the representativeness ordering of exemplars of a category. Experiments 1 and 2 employed an online reading time paradigm to examine the effect of context on the time it takes to establish an anaphoric reference between an exemplar and a category term. Experiment 1 demonstrated that context can change the relation between a category term and an exemplar at the time of comprehension. Experiment 2 showed that category terms presented in context generate graded goodness-of-example distributions of exemplars that are different from the distributions generated in the absence of explicit context. These distributions cannot be derived by assuming that the exemplar most strongly suggested by the context serves as the category representation. Experiment 3 employed a membership verification paradigm. Response time was found to be a function of degree of relatedness to the contextdependent category representation. Typicality, as determined in the absence of explicit context, had no effect on decision time. Several models, including some extensions of current semantic memory theories, are developed to account for the results of these experiments.     

A sociolinguistic approach to the belief-similarity model of racial attitudes

This study examined the belief-similarity model of prejudice from a sociolinguistic perspective. It was hypothesized that normatively regulated speech styles strongly affect observers' assumptions about the cultural background of the speaker. These linguistically based cultural assumptions were expected to override racial characteristics in controlling intergroup attitudes. Stimulus speech styles were Black English Vernacular (BEV) and Standard English (SE). Speech style was expected to strongly affect prejudicial attitudes, with such effects mediated by assumed cultural similarity. Racial label and speech style were expected to be most salient to ratings of “intimate” behavior and among more ethnocentric subjects. Subjects heard taped statements in either BEV or SE, ostensibly delivered by a White or a Black speaker. Subjects rated the speaker on perceived cultural similarity, general evaluation, perceived aggressiveness, and social distance. Speech style had a substantial main effect on each of these variables. Racial label had a marginally significant effect on evaluation, and interacted with ethnocentrism for perceived similarity and social distance. All effects of speech, race, and ethnocentrism were substantially attenuated or eliminated when similarity was used as a covariate. Thus, speech style had substantial effects on prejudice, as did race within more ethnocentric subjects. Both effects were largely mediated by assumed cultural similarity.     

Measurement of fear of the conditioned stimulus and of situational cues at several stages of two-way avoidance learning

In Experiment 1, subjects were trained in a signaled two-way avoidance task to a criterion of either 2, 10, or 20 consecutive avoidance responses. Subsequently, they were allowed to escape, in the absence of shock, from one compartment of the avoidance apparatus to an adjacent safe box. For one group at each criterion level, the conditioned stimulus (CS) was presented during these trials; for another group, it was not (NCS). The rate and level of learning of the escape response were taken to reflect the amount of fear of the CS and situational cues present at the end of avoidance training for the CS groups and the amount of fear of the situational cues alone for the NCS groups. Under the CS condition, all groups learned equally well; under the NCS condition, learning occurred only in the two-criterion group. This pattern of results suggests that, as avoidance training continued, differential reinforcement led to the formation of a discrimination so that a substantial amount of fear was elicited by the CS plus situational cues but only a minimal amount by the situational cues alone. Such a loss of fear of situational cues would, according to effective reinforcement theory, serve to maintain or even increase reinforcement as avoidance training progressed. The results of Experiment 2, by ruling out some alternative explanations, supported the interpretation that the learning of the instrumental escape response in the first experiment was based on prior fear conditioning.