MEMORY PROCESSES IN DELAYED SPATIAL DISCRIMINATIONS: RESPONSE INTENTIONS OR RESPONSE MEDIATION?

Pigeons were trained on a pair-comparison task in which left versus right choices were reinforced following different sequences of two center-key stimuli. Choice accuracy was higher when retention intervals occurred after the entire sequence than when they separated the two stimuli comprising it, and this effect occurred independently of whether the initial and terminal stimuli came from the same or different dimensions. The initial stimulus from the prior trial was a source of proactive interference only in groups for which the retention interval separated the two sequence stimuli. By contrast, differential delay-interval behavior was observed only in groups for which the retention interval followed presentation of the entire sequence. These results indicate that coding processes in delayed discriminations are influenced by the location of the retention interval, and that response mediation affects retention performances if the reinforced choice can be determined prior to the interval.     

El Greco's Eyesight: Interpreting Pictures and the Psychology of Vision

There is a common assumption about pictures, that seeing them produces in us something like the same effects as seeing the things they depict. This assumption lies behind much empirical research into vision, where experiments often expose subjects to pictures of things in order to investigate the processes involved in cognizing those things themselves. Can philosophy provide any justification for this assumption? I examine this issue in the context of Flint Schier's account of pictorial representation. Schier attempts to infer the assumption from what he takes to be the fundamental facts about picturing. I argue that there is no plausible form of Schier's basic claims from which the assumption can be inferred. I then reject a second argument, that by appealing to the assumption Schier could explain why it is impossible to depict a particular without depicting it as having certain properties. I conclude that those sympathetic to the assumption need to articulate and defend some version of it suited to their needs.     

Similarity in context

Similarity comparisons are highly sensitive to judgment context. Three experiments explore context effects that occur within a single comparison rather than across several trials. Experiment 1 shows reliable intransitivities in which a target is judged to be more similar to stimulus A than to stimulus B, more similar to B than to stimulus C, and more similar to C than to A. Experiment 2 explores the locus of Tversky’s (1977) diagnosticity effect in which the relative similarity of two alternatives to a target is influenced by a third alternative. Experiment 3 demonstrates a new violation of choice independence which is explained by object dimensions’ becoming foregrounded or backgrounded, depending upon the set of displayed objects. The observed violations of common assumptions to many models of similarity and choice can be accommodated in terms of a dynamic property-weighting process based on the variability and diagnosticity of dimensions.     

Need probability affects retention: A direct demonstration

Recent memory theory has emphasized the concept ofneed probability—that is, the probability that a given piece of learned information will be tested at some point in the future. It has been proposed that, in real-world situations, need probability declines over time and that the memory-loss rate is calibrated to match the progressive reduction in need probability (J. R. Anderson & Schooler, 1991). The present experiments were designed to examine the influence of the slope of the need-probability curve on the slope of the retention curve. On each of several trials, subjects memorized a list of digits, then retained the digits in memory for 1, 2, 4, 8, or 16 sec. Some trials ended with a recall test; other trials ended with the message, “no test.” In Experiment 1, the likelihood of encountering a memory test (i.e., the need probability) was made to either increase or decrease as the retention interval increased; in Experiment 2, need probability either was flat (invariant across retention intervals) or decreased as the retention interval increased. The results indicated that the shape of the need-probability curve influenced the slope of the retention curve (Experiment 1) and that the effect became larger as the experimental session progressed (Experiment 2). The findings support the notion that memory adapts to need probabilities and that the rate of forgetting is influenced by the slope of the need-probability curve. In addition, all of the forgetting curves approximated a power function, suggesting that need probability influences the slope but not the form of forgetting.     

The Journal of Abnormal Child Psychology at 25

This issue, redesigned in a new format, marks the beginning of Volume 25, the beginning of the silver anniversary year of the Journal of Abnormal Child Psychology. Data were compiled from the first 24 volumes to study changes over time, and Pearson correlations were calculated to determine linear trends in the journal's development The number of articles per volume has doubled, from about 25 to 50. In recent years the first authors of articles were more likely to be located outside the U.S. (up from about 5% to about 25%). Also, in recent years the first authors of articles were less likely to be affiliated with nonmedical school university departments and more likely to be affiliated with medical schools or research institutes. An introduction to this special 25th anniversary issue is provided.     

Are there nontrivial constraints on colour categorization?

In this target article the following hypotheses are discussed: (1) Colour is autonomous: a perceptuolinguistic and behavioural universal. (2) It is completely described by three independent attributes: hue, brightness, and saturation: (3) Phenomenologically and psychophysically there are four unique hues: red, green, blue, and yellow; (4) The unique hues are underpinned by two opponent psychophysical and/or neuronal channels: red/green, blue/yellow. The relevant literature is reviewed. We conclude: (i) Psychophysics and neurophysiology fail to set nontrivial constraints on colour categorization. (ii) Linguistic evidence provides no grounds for the universality of basic colour categories. (iii) Neither the opponent hues red/green, blue/yellow nor hue, brightness, and saturation are intrinsic to a universal concept of colour. (iv) Colour is not autonomous.     

In Vivo Hippocampal Acetylcholine Release During Exposure to Acute Stress

Hippocampal extracellular acetylcholine (ACh) and choline levels were evaluated using in vivo microdialysis in male Fischer 344 rats before, during, and following an 80-min exposure to two different stress conditions. Measurements were taken in rats restrained and immersed in a water bath containing either 37 degreesC (normothermic-restraint) or 20 degreesC (cold-restraint) water. Results were compared to normothermic-freely-moving rats. Cold-restrained rats displayed decreased ACh levels during cold exposure relative to both normothermic-restrained and normothermic-freely-moving rats. By the end of the cold exposure period and following removal from cold, ACh levels had returned to near-baseline values. Normothermic-restrained rats had levels similar to those of normothermic-freely-moving rats, except for a marked increase in ACh following removal from restraint. Cold-restrained rats displayed a gradual elevation in choline levels during cold stress, followed by a gradual decline after stress termination, whereas both normothermic-restrained and normothermic-freely-moving rats displayed gradual decreases during the microdialysis session. These findings demonstrate that central cholinergic neurotransmission can be altered by the application of, and removal from, acute stressors. In addition, the results suggest a possible relationship between the magnitudes of both the stressor and its cholinergic consequences.     

Client preferences for informed consent information

Thirty-five current therapy clients, 47 former clients, and 42 college students with no therapy experience rated 27 items in terms of importance for inclusion in informed consent discussions. The current and former client samples rated information about inappropriate therapeutic techniques, confidentiality, and the risks of alternative treatments as most important, and information about the personal characteristics of the therapist and the therapist's degree as least important. The results of this study provide evidence for differential informed consent disclosure practices.