The capacity of visual short-term memory is set both by visual information load and by number of objects

Previous research has suggested that visual short-term memory has a fixed capacity of about four objects. However, we found that capacity varied substantially across the five stimulus classes we examined, ranging from 1.6 for shaded cubes to 4.4 for colors (estimated using a change detection task). We also estimated the information load per item in each class, using visual search rate. The changes we measured in memory capacity across classes were almost exactly mirrored by changes in the opposite direction in visual search rate (r2=.992 between search rate and the reciprocal of memory capacity). The greater the information load of each item in a stimulus class (as indicated by a slower search rate), the fewer items from that class one can hold in memory. Extrapolating this linear relationship reveals that there is also an upper bound on capacity of approximately four or five objects. Thus, both the visual information load and number of objects impose capacity limits on visual short-term memory.     

Pathological gambling and personality disorders: an exploratory study with the IPDE

This article describes the most frequent personality disorders related to pathological gambling. Participants included 50 pathological gamblers assessed with the IPDE, and 50 normative subjects from the general population with the same demographic features (age, sex, and socioeconomic level). Thirty-two percent of the clinical sample (vs. the 8% of the normative sample) showed at least one personality disorder. The most prevalent disorders were Borderline (16%), followed by Antisocial, Paranoid, Narcissistic, and Non-specified (8% each). Gamblers with personality disorders presented an average of 1.5 disorders and they reported higher gambling severity and more severe symptoms of anxiety, depression and alcohol abuse. The implications of this study for clinical practice and research are discussed.     

Philosophy,mathematics, science and computation

Attempts to lay a foundation for the sciences based on modern mathematics are questioned. In particular, it is not clear that computer science should be based on set-theoretic mathematics. Set-theoretic mathematics has difficulties with its own foundations, making it reasonable to explore alternative foundations for the sciences. The role of computation within an alternative framework may prove to be of great potential in establishing a direction for the new field of computer science.Whitehead's theory of reality is re-examined as a foundation for the sciences. His theory does not simply attempt to add formal rigor to the sciences, but instead relies on the methods of the biological and social sciences to construct his world-view. Whitehead's theory is a rich source of notions that are intended to explain every element of experience. It is a product of Whitehead's earlier attempt to provide a mathematical foundation for the physical sciences and is still consistent with modern physics.A computer simulation language is, in fact, a theory of reality; one that is often based on extremely simplistic notions. Simulation languages have evolved from the various programming languages and not from the development of their underlying world-view. The use of an established theory of reality, such as Whitehead's, as the basis of a simulation language is proposed as a way of extending the usefulness of computer simulation as an experimental tool for the theory.The simulation language is a first step in this direction. Based on Whitehead's notion of concrescence and a formalization in the typed -calculus, provides a notation and method for the construction and simulation of real-world phenomena. Both philosophy and computer science stand to benefit from such an attempt. Whitehead's theory gains a testing tool, while computer science gains a significantly more advanced simulation language. In philosophical discussion, the merest hint of dogmatic certainty as to the finality of statement is an exhibition of folly. A. N. Whitehead,Process and Reality.     

Evaluating Multiple-Attribute Decision Support Systems

Differences in the perceived usefulness of five multiple-attribute decision support systems versus a basic spreadsheet are empirically assessed. Twenty-four college faculty members participated in a repeated measures experiment in which they used decision support software for personal computers to analyse semistructured multiple-attribute problems. The software packages employed were Criterium, Expert Choice, Logical Decision, VIMDA, VISA and the spreadsheet package Quattro Pro. A questionnaire was developed to assess user-friendliness of the software, confidence in the procedure implemented by the software, and users’ confidence in their results when employing the decision aids. Time to reach a decision was also measured. Significant differences were fund in the overall way users ranked these aids, in the perceived user-friendliness and the confidence in procedure among aids, and in the time it took to arrive at a result. Comments from users are also reported. © 1997 John Wiley & Sons, Ltd.     

Hippocampal formation lesions impair performance in an odor-odor association task independently of spatial context

The rodent hippocampal system is known to play an important role in memory. Evidence that this role is not limited to spatial memory has come from studies using a variety of non-spatial memory tasks. One example is the social transmission of food preference paradigm, a task in which rats learn an odor-odor association with no explicit spatial memory component. However, because training and testing in this task typically take place in the same environment, it is possible that memory for the spatial context in which odors are experienced during training is critical to subsequent retention performance. If this is the case, it might be expected that lesions of the hippocampal system would impair memory performance by disrupting the establishment of a representation of the training environment. We addressed this issue by training rats in one spatial context and then testing them either in the same or a different spatial context. Normal control rats performed equally well when tested in an environment that was the same or different from that used during training, and the retention impairment exhibited by rats with hippocampus plus subiculum lesions was equivalent in the two test environments. These results support the view that the hippocampal system is necessary for the flexible expression of nonspatial memories even when the spatial context in which the memory is acquired is not critical to retrieval.     

Eye movements and processing stages in reading: relative contribution of visual,lexical, and contextual factors

The independent and the combined influence of word length, word frequency, and contextual predictability on eye movements in reading was examined across processing stages under two priming-context conditions. Length, frequency, and predictability were used as predictors in multiple regression analyses, with parafoveal, early, late, and spillover eye movement measures as the dependent variables. There were specific effects of: (a) length, both on where to look (how likely a word was fixated and in which location) and how long to fixate, across all processing stages; (b) frequency, on how long to fixate a word, but not on where to look, at an early processing stage; and (c) predictability, both on how likely a word was fixated and for how long, in late processing stages. The source of influence for predictability was related to global rather than to local contextual priming. The contribution of word length was independent of contextual source. These results are relevant to determine both the time course of the influence of visual, lexical, and contextual factors on eye movements in reading, and which main component of eye movements, that is, location or duration, is affected.     

Syllables and morphemes: contrasting frequency effects in Spanish

Three types of sublexical units were studied in Spanish visual word recognition: the syllable, the basic orthographic syllabic structure (BOSS), and the root morpheme. In Experiment 1, using a lexical-decision task, a typical inhibitory effect of the first-syllable frequency was found (while keeping constant the BOSS frequency) as well as the word-frequency effect. Experiment 2 examined the role of both the BOSS frequency and the word frequency, also in a lexical-decision task. Syllable frequency was controlled. Both the BOSS frequency and the word frequency showed facilitatory effects. However, in Experiments 3A and 3B, a facilitatory effect of the root frequency (when controlling for BOSS frequency) and a null effect of BOSS frequency (when controlling for root frequency) were found, suggesting that the BOSS effect is in fact reflecting a morpheme effect. A review of the current models shows that it is difficult to integrate syllables and morphemes in a unique model.     

Space and time,not surface features,guide object persistence

Successful visual perception relies on the ability to keep track of distinct entities as the same persisting objects from one moment to the next. This is a computationally difficult process and its underlying nature remains unclear. Here we use the object file framework to explore whether surface feature information (e.g., color, shape) can be used to compute such object persistence. From six experiments we find that spatiotemporal information (location as a function of time) easily determines object files, but surface features do not. The results suggest an unexpectedly strong constraint on the visual system’s ability to compute online object persistence.     

Social identities and intergroup bias in immigrant and nonimmigrant children

Ethnic and American identity, as well as positivity and negativity toward multiple social groups, were assessed in 392 children attending 2nd or 4th grade in various New York City neighborhoods. Children from 5 ethnic groups were recruited, including White and Black Americans, as well as recent immigrants from China, the Dominican Republic, and the former Soviet Union. For ethnic minority children, greater positivity bias (evaluating one's ingroup more positively than outgroups) was predicted by immigrant status and ethnic identity, whereas negativity bias (evaluating outgroups more negatively than one's ingroup) was associated with increased age, immigrant status, and (among 4th graders only) ethnic identity. In addition, a more central American identity was associated with less intergroup bias among ethnic minority children.