Spatial frequency content of visual imagery

Three experiments employing the McCollough paradigm were conducted to determine the spatial-frequency content of visual imagery. In Experiment 1, large and reliable pattern-contingent color aftereffects were obtained after adaptation to visual imagery. The direction of the aftereffects indicated that subjects were adapting to higher spatial frequencies in their imagery. These results contrast with the data of Experiment 2, which demonstrate that color aftereffects obtained with adaptation to physically present stimuli are mediated by the fundamental spatial frequency components. The magnitude of the imagery-induced aftereffects in Experiment 1 equaled the magnitude of the externally induced aftereffects obtained in Experiment 2 with the same subjects. By blurring the to-be-imaged patterns (Experiment 3), the fundamental Fourier components became the salient perceptual features of the stimuli, and the direction of the imagery-induced aftereffects was reversed from that of Experiment 1, indicating that the spatial frequency content of the imagery had changed from higher to lower frequencies. Under normal viewing conditions, subjects use the higher spatial frequencies associated with the perceptually salient edges of stimuli to construct their images. The results of Experiments 1 and 3 are discussed in light of a current controversy over the nature of information representation in imagery, and it is concluded that support has been obtained for the analog model of visual imagery.     

Word associations and the development of lexical memory

Endel Tulving's distinction between “episodic” and “semantic” memory defines changes with age in word association norms in a more informative and more comprehensive manner than the syntactic classifications normally used. The principal development as subjects mature is an episodic-semantic shift. Young children associate primarily to the stimulus's perceived contexts, older subjects to its abstract semantic content.     

Methodological naturalism in the sciences

International Journal for Philosophy of Religion - Creationists have long argued that evolutionary science is committed to a dogmatic metaphysics of naturalism and materialism, which is based on...     

Evidence for a fixed capacity limit in attending multiple locations

A classic question concerns whether humans can attend multiple locations or objects at once. Although it is generally agreed that the answer to this question is “yes,” the limits on this ability are subject to extensive debate. According to one view, attentional resources can be flexibly allocated to a variable number of locations, with an inverse relationship between the number of selected locations and the quality of information processing at each location. Alternatively, these resources might be quantized in a “discrete” fashion that enables concurrent access to a small number of locations. Here, we report a series of experiments comparing these alternatives. In each experiment, we cued participants to attend a variable number of spatial locations and asked them to report the orientation of a single, briefly presented target. In all experiments, participants’ orientation report errors were well-described by a model that assumes a fixed upper limit in the number of locations that can be attended. Conversely, report errors were poorly described by a flexible-resource model that assumes no fixed limit on the number of locations that can be attended. Critically, we showed that these discrete limits were predicted by cue-evoked neural activity elicited before the onset of the target array, suggesting that performance was limited by selection processes that began prior to subsequent encoding and memory storage. Together, these findings constitute novel evidence supporting the hypothesis that human observers can attend only a small number of discrete locations at an instant.     

The impact of parental attachment and supervision on fear of crime among adolescent males

This paper examines the effect of parental attachment and supervision on fear of crime among adolescent males. Earlier work has suggested that feelings of powerlessness and association with deviant peers have a significant impact on adolescent fear of crime. As the nature of the parent-adolescent relationship is also a key predictor of adolescent self-concept and quality of peer relationships, we felt that parental attachment and supervision should also impact fear of crime. Using self-report surveys from 318 incarcerated adolescent males, we examine the effect of parental attachment and supervision, along with other demographic and contextual variables, on fear of criminal victimization, perceived safety, and perceptions of risk. The results indicate that those boys who are most attached to their parents are less fearful of criminal victimization and feel safer in their environment than do their counterparts with weaker parental attachments. Additionally, those boys whose parents supervise them closely are more fearful of criminal victimization, but have lower levels of perceived risk of victimization. Implications and ramifications for social policies and future research are also discussed.     

"Mindless" decision making as a failure of contextual reasoning

People often make decisions without reference to vital information, even when such information is readily available. In the present research, the authors addressed the possibility that this tendency may derive from failure to have pertinent information immediately available in the decision context. Participants rated the utility of decisions in either the presence or absence of simple pertinent information. The information provided required no training and was relatively obvious (e.g., if money is spent on a given item, that money will not be available for other expenditures). Presentation of such information in the immediate context of decisions significantly improved participants' abilities to understand their negative consequences. These results indicate that the presentation of pertinent information in immediate decision contexts, even information that is already available through participants' long-term memory, can improve the understanding of decision situations and reduce "mindlessness" in decision processes.