Intra- and cross-dimensional visual search for single-feature targets

Cross-dimensional visual search for single-feature targets that differed from the distractors along two dimensions (color and orientation) was compared with intradimensional search for targets that differed from the distractors along a single dimension (either orientation or color). The design of the first three experiments differed from those of previous studies in that participants were required to respond differently to each of the targets. Experiments 1-3 were similar except that in Experiment 1, the distractors were homogeneous; in Experiment 2, two types of distractors were used in equal proportions; and in Experiment 3, two types of distractors were used but one of the distractors was a singleton. The findings, contrary to those of previous studies, revealed that cross-dimensional search is at least as efficient and for some targets even more efficient than intradimensional search. These results suggest that the details of stimulus-to-response mapping are essential in comparing intra- and cross-dimensional tasks. Experiment 4 used a priming design and did not support an explanation based on grouping processes. We outline an explanation for all the findings based on a recent cross-dimensional response selection model by Cohen and Shoup (1997).     

From parallel to serial processing: a computational study of visual search

A novel computational model of a preattentive system performing visual search is presented. The model processes displays of lines, reproduced from Wolfe, Friedman-Hill, Stewart, and O'Connell's (1992) and Treisman and Sato's (1990) visual-search experiments. The response times measured in these experiments suggest that some of the displays are searched serially, whereas others are scanned in parallel. Our neural network model operates in two phases. First, the visual displays are compressed via standard methods (principal component analysis), to overcome assumed biological capacity limitations. Second, the compressed representations are further processed to identify a target in the display. The model succeeds in fast detection of targets in experimentally labeled parallel displays, but fails with serial ones. Analysis of the compressed internal representations reveals that compressed parallel displays contain global information that enables instantaneous target detection. However, in representations of serial displays, this global information is obscure, and hence, a target detection system should resort to a serial, attentional scan of local features across the display. Our analysis provides a numerical criterion that is strongly correlated with the experimental response time slopes and enables us to reformulate Duncan and Humphreys's (1989) search surface, using precise quantitative measures. Our findings provide further insight into the important debate concerning the dichotomous versus continuous views of parallel/serial visual search.     

Neural dynamics of perceptual order and context effects for variable-rate speech syllables

How does the brain extract invariant properties of variable-rate speech? A neural model, called PHONET, is developed to explain aspects of this process and, along the way, data about perceptual context effects. For example, in consonant-vowel (CV) syllables, such as /ba/ and /wa/, an increase in the duration of the vowel can cause a switch in the percept of the preceding consonant from /w/ to /b/ (J.L. Miller & Liberman, 1979). The frequency extent of the initial formant transitions of fixed duration also influences the percept (Schwab, Sawusch, & Nusbaum, 1981). PHONET quantitatively simulates over 98% of the variance in these data, using a single set of parameters. The model also qualitatively explains many data about other perceptual context effects. In the model, C and V inputs are filtered by parallel auditory streams that respond preferentially to the transient and sustained properties of the acoustic signal before being stored in parallel working memories. A lateral inhibitory network of onset- and rate-sensitive cells in the transient channel extracts measures of frequency transition rate and extent. Greater activation of the transient stream can increase the processing rate in the sustained stream via a cross-stream automatic gain control interaction. The stored activities across these gain-controlled working memories provide a basis for rate-invariant perception, since the transient-to-sustained gain control tends to preserve the relative activities across the transient and sustained working memories as speech rate changes. Comparisons with alternative models tested suggest that the fit cannot be attributed to the simplicity of the data. Brain analogues of model cell types are described.     

Peer Status in the Middle School: A Natural Treatment for Unequal Participation

The focus of this study is on the problem of unequal participation of students within small cooperative learning groups in middle-school classrooms. According to previous research using Status Characteristic Theory, this unequal participation stems from differential expectations for competence based on academic and peer status. Previous research had also found that in classrooms where rank on these two status orders was uncorrelated (incongruent classrooms), problems of unequal participation were less severe. This study involved systematic observations of students in working groups in four middle-school science classrooms. The derivation of hypotheses required an extension of Status Characteristic Theory to handle three-to-five-person groups working in a multicharacteristic situation. The results showed good support for hypotheses explaining the effect of incongruence in the social structure on participation of low-status students. Incongruent classrooms had fewer small groups that were highly differentiated on status. Moreover, the degree of status differentiation in the groups was a direct predictor of the participation rates of the low-status students. Thus, the less differentiated groups in incongruent classrooms showed fewer status problems. As a practical matter, the tendency of students to construct peer status orders that are independent of academic status acts as a natural treatment for unequal participation.     

The Role of Psychological Characteristics in the Relation Between Socioeconomic Status and Perceived Health1

Separate analyses of United States and Finnish samples demonstrate a graded (almost linear) relation between socioeconomic status (SES) and risk of poor perceived health. In both studies, positive psychological factors (greater social support; less anger, depression, and perceived stress) and beneficial health practices (nonsmoking; drinking and exercising moderately) were associated with both higher levels of SES and better self-reported health. Psychological and health practice variables were both able to account for some of the SES and poor health gradient. However, contrary to expectations, these factors did not play a more important role in explaining decreased risk at the middle and highest levels of SES, and instead may be most important at lowest levels.     

The impact of personality on the reporting of unfounded symptoms and illness.

This study examined the role of personality in the reporting of symptoms and illness not supported by underlying pathology. After assessment of the Big Five personality factors, 276 healthy volunteers were inoculated with a common cold virus. On each of the following 5 days, objective indicators of pathology, self-reported symptoms, and self-reported illness onset were assessed. Neuroticism was directly associated with reports of unfounded (without a physiological basis) symptoms in individuals at baseline and postinoculation in those with and without colds. Neuroticism was also indirectly associated with reports of unfounded illness through reports of more symptoms. Openness to Experience was associated with reporting unfounded symptoms in those with verifiable colds, whereas Conscientiousness was associated with reporting unfounded illness in those who were not ill.     

Control Beliefs and Faith as Stress Moderators for Korean American Versus Caucasian American Protestants

Examined relationships among negative life events, four locus of control attributions (Internality, Powerful Others, Chance, and God Control), and psychological distress for Korean American versus Caucasian American Protestants. Negative events and Powerful Others beliefs were positively related to distress, whereas Internality was negatively related to distress. Ethnicity and God Control interacted: The relationship between God Control beliefs and anxiety was negative for Caucasians but positive for Koreans. Three-way interactions (Ethnicity × Locus of Control × Negative Events) also emerged. As Caucasians' Powerful Others beliefs increased, the positive relationship between negative events and depression became stronger; Koreans' Powerful Others beliefs had no such effect. As Caucasians' God Control beliefs increased, the negative event–depression relationship changed from positive to negative; the reverse was true for Koreans. Findings support the value of assessing ethnoculture and religiousness in stressful life events research.     

Do animals have rights?

A right, unlike an interest, is a valid claim, or potential claim, made by a moral agent, under principles that govern both the claimant and the target of the claim. Animals cannot be the bearers of rights because the concept of rights is essentially human; it is rooted in and has force within a human moral world.     

Personality in panic disorder with agoraphobia: a Rorschach study.

In this study, we tested several hypotheses derived from self psychology (Diamond, 1987) regarding personality features of patients suffering from panic disorder and agoraphobia (PDA). PDA patients are thought to suffer from a deficit in negative affect-regulating capacity, surrounded by defenses such as avoidance, repression, denial, and reaction formation against dependency needs. These defenses are thought to lead to a greatly impoverished affective life. The Rorschach Comprehensive System was used to assess the personality features of avoidance, restricted affective life, and reaction formation against dependency needs. We found evidence for the presence of a highly avoidant information-processing style (86% of protocols had lambda [L] greater than .99) and a constricted affective life (low weighted sum color [WSumC] and low affective ratio [Afr]). Our results were consistent with the hypothesis of reaction formation against dependency needs (low food content [Fd]). Findings are discussed in light of studies that found a high incidence of avoidant personality disorder in PDA patients.     

Very long-term memory for knowledge acquired at school and university

Recent research into the very long-term retention of knowledge originally acquired during the process of formal education at school and university has demonstrated that such knowledge may be retained at high levels over very long retention intervals. The pattern of retention typically takes the form of a comparatively short period marked by forgetting (lasting between 1 and 6 years) followed by a long period of stable retention (usually longer than 30 years). For courses taken at school the level attained over a series of courses (e.g. in learning a foreign language or studying mathematics) is an important determinant of long-term retention. Students who attain moderate or advanced levels of learning show high levels of retention with very little forgetting, whereas students who attain only lower levels of learning show steady forgetting, and after a period of 6 years retain very little knowledge. Similar patterns of retention are present for university students taking single courses in science and literature subjects, and students with higher grades retain more knowledge although the reliable relationship here, between grade obtained and amount remembered, is weak and accounts for only small portions of the variance in retention. Taken together these findings suggest that the retention of knowledge acquired through formal education persists over longer periods of time than popularly believed. Recent theory proposes that these long-lasting effects of education are partly related to the types of learning schedules followed during acquisition and partly related to the nature of the to-be-acquired knowledge, and to whether or not knowledge can be represented schematically.