Target position and practice in the identification of letters in varying contexts: A word superiority effect

A forced-choice detection paradigm controlling for postperceptual inference was used to investigate letter identification in three-position displays. Letters from a predesignated set of four targets appeared singly, in strings of noise characters, in unpronounceable nonsense strings, and in words. Subjects knew which context would occur, but did not know which of the three display positions would contain the target. Correct detection data were collected at constant exposure duration over five testing sessions. Overall identification accuracy was higher in words than in all other contexts, the first word superiority effect to be found with targets specified in advance since Reicher’s (1969). This effect remained constant over sessions. An interaction between context type and target position showed enhanced accuracy for initial and terminal letters in words, but depressed accuracy at initial and terminal positions in other contexts. This was interpreted to mean that prior knowledge of context is used to alter the dynamics of perceptual analysis.     

The Anatomy of Revolutionists

A questionnaire containing 62 items relating to the New Left and 28 items measuring anomia, authoritarianism, and Machiavellianism was given to 153 entering freshmen at Columbia in the fall of 1968. The five factors emerging from a factor analysis of responses to the items were labeled: New Left Philosophy, Revolutionary Tactics, Machiavellian Tactics, Machiavellian Cynicism, and Traditional Moralism. Students who had been politically active prior to coming to college scored higher than the rest of the group on New Left Philosophy, Revolutionary Tactics, and Machiavellian Cynicism, but scored lower on Machiavellian'Tactics and Traditional Moralism. In the spring of 1969, a revised set of items was given to students in introductory psychology classes at Columbia University and New York University. While the findings from these subjects replicated those found with the Columbia freshmen, they showed subtle differences which led to speculations about the radicalization process. Also discussed are the relationships between the nature of political participation and all of the factors, with special emphasis on the discrepancy between Machiavellian Tactics and Cynicism.     

Characteristics of Suicidality Among Adolescents

The identification of high-risk adolescent suicide attempters in a population of depressed and suicidal adolescents is of crucial importance. This retrospective study examined characteristics of suicidality (recent and lifetime, active and passive) and psychopathology (depression, aggression, impulsivity, stressful life events, SCL-90 dimensions) among four groups of depressed adolescent outpatients: (1) suicide attempters who required medical treatment (n = 84), (2) suicide attempters who did not require medical treatment (n = 57), (3) suicidal ideators who had never made a suicide attempt (n = 40), and (4) nonsuicidal patients (n = 44). Results indicate that the nonsuicidal group could be differentiated from the three suicidal groups on the basis of suicidality and psychopathology, and that the three suicidal groups could be differentiated from one another on the basis of suicidality but not psychopathology. These findings are discussed in terms of the usefulness of certain self-report measures of suicidality for identifying suicidal adolescents and for differentiating among them. Furthermore, the findings suggest that psychopathological factors do not determine which suicidal adolescents make a medically dangerous suicide attempt and which do not.     

Salience drives overt selection of two equally relevant visual targets

In the present study, we investigated whether salience determines the sequence of selection when participants search for two equally relevant visual targets. To do this, attentional selection was tracked overtly as observers inspected two items of differing physical salience: one a highly salient color singleton, and the other a less salient shape singleton. Participants were instructed to make natural eye movements in order to determine whether two line segments contained within the two singletons were oriented in the same or in different directions. Because both singleton items were task-relevant, participants had no reason to inspect one item before the other. As expected, observers fixated both targets on the majority of trials. Critically, saccades to the color singleton preceded saccades to the less salient shape singleton on the majority of trials. This demonstrates that the order of attentional object selection is largely determined by stimulus salience when task relevance is equated.     

Familiarity seekers are fast and novelty seekers are slow

Christie and Klein () demonstrated that a familiar item (word) rapidly attracts attention when presented simultaneously with an unfamiliar item (nonword). However, this finding has never been replicated. The current study is an attempt at such a replication. Participants were presented a familiar word and unfamiliar nonword in the experimental condition. At varying times after stimulus onset one of the items moved, and the participant reported the direction of the movement. A replication of Christie and Klein would be obtained if performance was better for movement discrimination of the familiar item shortly after onset but not at later intervals. The original finding was replicated in fast participants while slower participants show a different effect. A potential individual difference variable is suggested to explain this difference between the fast and slow participants.     

Visuospatial function in the beagle dog: an early marker of cognitive decline in a model of human aging and dementia

Visuospatial learning and memory impairments are an early marker for age-related cognitive decline and Alzheimer's disease. Similar to humans, aged dogs show visuospatial learning and memory deficits (). One hundred and nine beagle dogs ranging between 0.25 and 11.99 years were tested on a visuospatial delayed non-matching to position (DNMP) task to better characterize the progression of visuospatial deficits in the dog. Age predicted 48.2% of the variability in learning the DNMP, with dogs ranging from 1 to 11.99 years generally making more errors with increasing age. By contrast, puppies (<1 year) likely were showing developmental deficits, possibly due to an immature prefrontal cortex. Mild visuospatial deficits were detected by 6 years, which precedes the typical onset of amyloid-beta (Abeta) accumulation in the dog brain by two years, and can serve as an early marker for cognitive decline in the dog. These findings suggest that (1) age-related changes in visuospatial function in the dog models that seen in humans, further validating the dog as a model for human aging and dementia; and (2) other mechanisms, such as oxidative stress, soluble Abeta oligomers or cholinergic deficits, are likely contributing to the early impairment.