Time courses in visual-information processing: Some empirical evidence for inhibition

Summary In the literature two different views on the time course of activation of recognition units — hypothetical units that represent identity information — are proposed. The first view assumes that the recognition units accumulate activation gradually over time. The second assumes that the activation levels increase fast initially and then start to decrease. Hagenzieker and Van der Heijden (1990) have proposed a more general information-processing model, which is compatible with both views. In this model a treshold determines what type of time course will be obtained. For below-threshold-activation values a gradual accumulation of activation will be found; for above-threshold values activation levels will first increase and then, because of inhibition, decrease. This model served as a starting-point for the present paper. Elaboration of this model led to two testable hypotheses with regard to identification performance. The first prediction is that evidence for inhibition should be observed only under relatively bright luminance conditions. The second is that, given inhibition, the amount of the effect of this inhibition should increase over time. A partial-report bar-probe task was used to test the predictions. The experiment involved two luminance conditions and the information was sampled at two different moments in time. To control for possible localization artefacts a digit-naming task was also used. Evidence for inhibition was found in both luminance conditions. In accordance with the model the amount of the effect of inhibition increased over time.     

Visual perception and the guidance of locomotion without vision to previously seen targets

Two experiments were performed to assess the accuracy and precision with which adults perceive absolute egocentric distances to visible targets and coordinate their actions with them when walking without vision. In experiment 1 subjects stood in a large open field and attempted to judge the midpoint of self-to-target distances of between 4 and 24 m. In experiment 2 both highly practiced and unpracticed subjects stood in the same open field, viewed the same targets, and attempted to walk to them without vision or other environmental feedback under three conditions designed to assess the effects on accuracy of time-based memory decay and of walking at an unusually rapid pace. In experiment 1 the visual judgments were quite accurate and showed no systematic constant error. The small variable errors were linearly related to target distance. In experiment 2 the briskly paced walks were accurate, showing no systematic constant error, and the small, variable errors were a linear function of target distance and averaged about 8% of the target distance. Unlike Thomson's (1983) findings, there was not an abrupt increase in variable error at around 9 m, and no significant time-based effects were observed. The results demonstrate the accuracy of people's visual perception of absolute egocentric distances out to 24 m under open field conditions. The accuracy of people's walking without vision to previously seen targets shows that efferent and proprioceptive information about locomotion is closely calibrated to visually perceived distance. Sensitivity to the correlation of optical flow with efferent/proprioceptive information while walking with vision may provide the basis for this calibration when walking without vision.     

Saccadic reaction times of dyslexic and age-matched normal subjects

Saccadic reaction times (SRT) were measured in a simple task: subjects had to make saccades from a central fixation point to peripheral targets, which appeared randomly 4 deg to the left or to the right. In the first test the fixation point went off before the target appeared (gap trials); in the second test it remained on the screen (overlap trials). The distribution of SRTs for trained normal adults (N = 4), untrained normal adults (N = 11), untrained normal children (aged 9-11 years, N = 9), untrained normal teenagers (aged 15-17 years, N = 8), dyslexic children (aged 9-11 years, N = 15), and dyslexic teenagers (aged 15-17 years, N = 5) were compared, with special emphasis on the number of express saccades, ie saccades with extremely short reaction times (100-120 ms, under the present conditions). In normal adults with the gap paradigm, the distribution of reaction times typically exhibits two or three modes (express saccades, fast regular saccades, and very few slow regular saccades), whereas in the overlap paradigm only one or two modes (few fast regular saccades and many slow regular saccades) are obtained. On average, normal children produce more express saccades than naive normal adults. Dyslexic children produce more express saccades than the normal age-matched controls. Among the dyslexic children, four different types of abnormalities in their reaction times were encountered. The group of dyslexic teenagers was characterized by a larger number of express saccades at the expense of fast regular saccades in gap trials and by fewer express saccades and fewer fast regular saccades in overlap trials when compared to the age-matched control group. It is concluded that the abnormal patterns of saccadic reaction times reflect defects in the system of visual attention and/or in its control over the oculomotor system, rather than indicating a defect in the oculomotor system itself. In this context, symptoms of dyslexia appear as a combination of attentional deficits and irregular timing of saccadic eye movements.     

Abbreviated measures of sex role egalitarian attitudes

Alternate 25-item short forms of the Sex-Role Egalitarianism Scale (SRES) were developed and examined for psychometric quality using data from a sample of 608 students. Internal consistency coefficients were .94 and .92 for the two forms, stability coefficients with a three-week test-retest in terval were .88 for each, and the coefficient of equivalence or alternate forms reliability was .87. As expected, females scored significantly more egalitarian than males on both short forms, and results of factor analyses pointed to unidimensional measurement of a single construct for males, females, and the total sample. Additional support for reliability and validity is overviewed. The abbreviated SRES forms appear to provide a psychometrically sound and time-efficient means for assessing egalitarian attitudes.     

Training in law and behavioral sciences: Issues from the criminal justice perspective

Interdisciplinary training in behavioral sciences and the law should be appropriate for a criminal justice education program. However, adopting such an interdisciplinary goal is problematic because the divisions in the types of educational curricula need to be confronted. The relationships of the criminal justice academic community with the profession, and of the behavioral sciences with present criminal justice policies, must also be addressed in the attempt to develop familiarity with behavioral sciences and their legal relevance in shaping the criminal justice system. These factors may hinder extensive implementation of such training. Suggestions are made for incorporating this raining in a criminal justice curriculum.     

Feigned insanity in nineteenth-century America: Tactics,trials, and truth

Feigned insanity in nineteenth-century America is appraised through a review of the medical and legal literature. The authors focus on the explanations for feigning, procedures used in uncovering feigning, and the role of feigning in the courtroom. This discussion of feigned insanity demonstrates the remarkable consistency of approach to this form of malingering over the past 200 years.     

Who's to blame: Attributions regarding causality in spouse abuse

Spouse abuse is examined from the perspective of attribution theory. Aggressors are seen as attributing their violent behavior to external causes, whether by projecting their negative traits onto their spouses or by finding excuses which blame temporary environmental factors. In contrast, victims often attribute the abuse to defects within themselves or situational factors affecting their spouses. The attribution process seems affected by the frequency, intensity and duration of the abuse, with temporal factors playing an important role in the woman's internalizing style. Furthermore, inadequate early coping efforts play a powerful role in establishing cognitive-perceptual patterns that serve to perpetuate the abuse.     

The effects of polydrug use with and without cocaine on mother-infant interaction at 3 and 6 months

The face-to-face interactions of 43 polydrug-with-cocaine-using mothers and their infants at 3 and 6 months were compared to 17 non-cocaine-but other-drug-using mothers and 21 mothers who used no drugs during their pregnancy. Coders blind to mothers' drug use status scored 3 min of face-to-face interactions for 16 measures of maternal and infant interactive behaviors. A principal component of 7 behaviors formed a measure of maternal attentiveness; a principal component of 5 behaviors formed a measure of mother-infant dyadic organization; and a principal component of 4 behaviors formed a measure of infant readiness to interact. A measure of maternal interruption was computed as the mean standard score of 3 additional interruptive behaviors. At 3 and 6 months, polydrug-with-cocaine-using mothers were less attentive to interactions, and polydrug-with-cocaine-using mothers and their infants engaged in fewer dyadic interactions than either non-cocaine or non-drug-using mothers. Compared to 3 months, polydrug-with-cocaine-using mothers at 6 months were less attentive to interactions and more frequently interrupted interactions by looking away, redirecting the infant, or withdrawing, whereas non-cocaine-using and non-drug- using mothers showed no change or an improvement in attentiveness to interactions and a decrease in interruptions. No differences emerged in the interactive behaviors of the infants of polydrug- with-cocaine-using, non-cocaine-using, or non-drug-using mothers. Cocaine use represents a significant risk for diminished parental attentiveness and responsiveness to infants and for diminished interactiveness in infants.     

Failure to detect changes to attended objects in motion pictures

Our intuition that we richly represent the visual details of our environment is illusory. When viewing a scene, we seem to use detailed representations of object properties and interobject relations to achieve a sense of continuity across views. Yet, several recent studies show that human observers fail to detect changes to objects and object properties when localized retinal information signaling a change is masked or eliminated (e.g., by eye movements). However, these studies changed arbitrarily chosen objects which may have been outside the focus of attention. We draw on previous research showing the importance of spatiotemporal information for tracking objects by creating short motion pictures in which objects in both arbitrary locations and the very center of attention were changed. Adult observers failed to notice changes in both cases, even when the sole actor in a scene transformed into another person across an instantaneous change in camera angle (or “cut”).