Raster versus calligraphic display devices for assessing visual performance: The influence of stimulus area and uncertainty

Sixty-hertz raster scan monitors provide relatively inexpensive solutions to problems associated with presenting complex visual stimuli. However, they restrict the user to displays in which stimulus characteristics cannot be changed more often than once every 16.67 msec. Calligraphic monitors allow very high frame rates, but not the generation of complex or chromatic images (unless very expensive monitors are purchased). A method is reported for increasing the frame rate of some raster monitors at the expense of the number of lines that are painted. Also, data relating to the influence of such a modification on visual performance is presented.     

Normalization of irrelevant dimensions in stimulus comparisons

When subjects compared two multidimensional stimuli with respect to a single (relevant) dimension in a same-different task, variation in the irrelevant dimension systematically affected reaction times. For same trials, reaction times increased monotonically with the amount of disparity between the stimuli on the irrelevant dimension. The dimensions were heights and widths of ellipses or hues and tints of color patches. The results were interpreted in terms of a normalization process that internally transforms the irrelevant dimensions of the two stimuli until they are equal. The amount of normalization, and hence same reaction time, increased with increasing disparity on the irrelevant dimension. These results suggest that in order to decide that two objects are equivalent in some criterial respect, it is often necessary to normalize irrelevant disparities.     

Temperament, distraction, and learning in toddlerhood

The word- and nonword-learning abilities of toddlers were tested under various conditions of environmental distraction, and evaluated with respect to children's temperamental attentional focus. Thirty-nine children and their mothers visited the lab at child age 21-months, where children were exposed to fast-mapping word-learning trials and nonlinguistic sequential learning trials. It was found that both word- and nonword-learning were adversely affected by the presentation of environmental distractions. But it was also found that the effect of the distractions sometimes depended on children's level of attentional focus. Specifically, children high in attentional focus were less affected by environmental distractions than children low in attentional focus when attempting to learn from a model, whereas children low in attentional focus demonstrated little learning from the model. Translationally, these results may be of use to child health-care providers investigating possible sources of cognitive and language delay.     

How do health and biological age influence chronological age and sex differences in cognitive aging: moderating, mediating, or both?

Much research on cognitive competence in normal older adults has documented age and sex differences. The authors used new cross-sectional data from the Victoria Longitudinal Study (VLS) (n=386; age 61 to 95 years) to examine how health and biological age influence age and sex differences in cognitive aging. The authors found evidence for both moderating and mediating influences. Age differences were moderated by health status, such that the negative effects of age were most pronounced among participants of relatively better health. Sex differences were moderated by health and were more pronounced among participants reporting comparatively poorer health. Although health mediated a notable amount of age-related cognitive variation, BioAge mediated considerably more variance, even after statistical control for differences in health. A complex pattern emerged for the mediation of sex differences: Although BioAge accounted for sex-related variation in cognitive performance, health operated to suppress these differences. Overall, both health and BioAge predicted cognitive variation independently of chronological age.     

Prawn-in-a-tube procedure: habituation or associative learning in cuttlefish?

The prawn-in-a-tube procedure (J. B. Messenger, 1973a) has been used almost exclusively to study associative learning in cuttlefish. In two experiments, the authors sought to determine whether the decline in attack responses observed in this procedure was best accounted for by habituation or associative learning. Results of Experiment 1 revealed an asymmetrical stimulus-specificity effect that could be interpreted as either an instance of habituation or of associative learning. Results of Experiment 2 demonstrated that the response decline could not be reversed following the presentation of a dishabituatory stimulus. The combined results of these experiments support the conclusion that the response decline is best viewed as a resulting of associative processes. The authors considered whether the response decline represents extinction or passive avoidance.     

Beyond the optimal contact strategy: a reality check for the contact hypothesis

The contact hypothesis proposes that interaction between members of different groups reduces intergroup prejudice if--and only if--certain optimal conditions are present. For over 50 years, research using this framework has explored the boundary conditions for ideal contact and has guided interventions to promote desegregation. Although supporting the contact hypothesis in principle, the authors critique some research practices that have come to dominate the field: (a) the prioritizing of the study of interactions occurring under rarefied conditions, (b) the reformulation of lay understandings of contact in terms of a generic typology of ideal dimensions, and (c) the use of shifts in personal prejudice as the primary measure of outcome. The authors argue that these practices have limited the contact hypothesis both as an explanation of the intergroup dynamics of desegregation and as a framework for promoting social psychological change. In so arguing, the authors look toward a complementary program of research on contact and desegregation.     

Past experience influences object representation in working memory

The nature of object representation in working memory is vital to establishing the capacity of working memory, which in turn shapes the limits of visual cognition and awareness. Although current theories discuss whether representations in working memory are feature-based or object-based, no theory has considered the role of past experience. However, work with humans and non-human primates suggests that once participants learn which features are important for category membership, these diagnostic features become more salient than non-diagnostic features in long-term memory and object recognition. Critically, the brain areas involved in this diagnosticity effect are also recruited during working memory tasks. We report two experiments testing whether a diagnosticity effect exists in working memory; and whether it is present when visual information is encoded into working memory, or if it is the result of maintenance within working memory. Results showed a diagnosticity effect which was present at encoding. Maintenance did not influence the nature of object representation in working memory. These findings show that the meaning we glean from our past experience has a profound influence on the nature of object representation in working memory.     

Confirmatory factor structure and measurement invariance of the Memory Compensation Questionnaire

Recent research with the Memory Compensation Questionnaire (MCQ) has examined changes, functions, and correlates of compensatory strategy use in older adults. The twofold aim of this study was to test (a) the hypothesized structure of the MCQ and (b) structural equivalence across age, gender, and time. The 7-scale MCQ was designed to measure 5 compensatory mechanisms and 2 general aspects of compensatory awareness. The authors assembled a 3-wave (6-year) sample (N = 521; age = 55-85 years) from the Victoria Longitudinal Study. The results of structural equation modeling supported (a) the a priori structure of the MCQ and (b) the inference of measurement invariance across the 3 dimensions. Accordingly, the MCQ is available for measuring self-reported efforts to compensate for everyday memory losses.     

Optimal choice of rater terms I: Theory

How can an investigator choose a good team of raters to use for measuring a continuous variable when each available rater produces only dichotomous responses? We formulate an underlying model, define an index of goodness for rater teams in terms of average mean square error of the estimate, develop a new estimator and derive the optimal rater terms. The optimal raters have characteristic curves which are linear in form and satisfy the requirements for a Guttman scale.     

TouchStat: A Monte Carlo program for calculating sequential touching probabilities

A growing number of child cognition researchers are using an object-manipulation, sequential-touching paradigm to explore young children’s conceptual abilities. Within this paradigm, it is essential to distinguish children’s intracategory touching sequences from those expected by chance. The sequentialtouching approach is congruent with a permutation testing model of statistical inference and is best modeled by sampled permutations as derived from Monte Carlo procedures. In this article, we introduce a computer program for generating Monte Carlo sequential-touching simulations. TouchStat permits users to determine their own specifications to simulate sequential touching to category exemplars across a wide range of task parameters. We also present Monte Carlo chance probabilities for the standard two-category, four-exemplar task, with sequences up to 30 touches long. Finally, we consider broader applications of the TouchStat program.