Revisiting preview search at isoluminance: new onsets are not necessary for the preview advantage

It has been argued that search performance under preview conditions relies on automatic capture by luminance onsets (Donk & Theeuwes, 2001). We present three experiments in which preview search was examined with both isoluminant and nonisoluminant items (e.g., as defined by luminance onsets). Experiment 1 provided evidence against the automatic capture of attention by onsets. Search benefited when onset previews were followed by new onset stimuli, as compared with a full-set baseline matched for the number of new onsets but in which half the distractors appeared simultaneously at isoluminance. Furthermore, both Experiments 1 and 2 established a preview advantage when isoluminant targets followed onset previews, when compared with appropriate full-set baselines. Experiment 3 replicated this result, while showing that the preview benefit was disrupted by dual-task interference. The data indicate that new onsets are not necessary to generate a preview advantage in search. We discuss the data in terms of search's benefiting from active inhibition of old onset-defined stimuli.     

Counterfactual thinking and the first instinct fallacy

Most people believe that they should avoid changing their answer when taking multiple-choice tests. Virtually all research on this topic, however, has suggested that this strategy is ill-founded: Most answer changes are from incorrect to correct, and people who change their answers usually improve their test scores. Why do people believe in this strategy if the data so strongly refute it? The authors argue that the belief is in part a product of counterfactual thinking. Changing an answer when one should have stuck with one's original answer leads to more "if only . . ." self-recriminations than does sticking with one's first instinct when one should have switched. As a consequence, instances of the former are more memorable than instances of the latter. This differential availability provides individuals with compelling (albeit illusory) personal evidence for the wisdom of always following their 1st instinct, with suboptimal test scores the result.     

When a reappearance is old news: visual marking survives occlusion

Performance in a visual search task becomes more efficient if half of the distractors are presented before the rest of the stimuli. This "preview benefit" may partly be due to inhibition of the old (previewed) items. The preview effect is abolished, however, if the old items offset briefly before reappearing (D. G. Watson & G. W. Humphreys, 1997). The authors examined whether this offset effect still occurred if the old items undergo occlusion. Results show that a preview benefit was found when the old items were occluded but not otherwise, consistent with the idea of top-down attentional inhibition being applied to the old items. The preview benefit is attenuated, however, by movement of the irrelevant stimuli in the displays.     

On the efficiency of drawing computer-generated line stimuli: Rectangles can be faster than lines

A simple method is presented for optimizing the efficiency of drawing line stimuli in Turbo Pascal. It involves the substitution of Rectangle and Bar commands for Line commands and results in time savings of up to 90%. The savings are most consistent for horizontal lines, although some savings may also be made for vertical lines. The effects of different graphics libraries, graphics modes, and hardware configurations are discussed. The method proves especially useful in improving the spatiotemporal resolution of on-line-generated motion displays.     

Early visual tagging: effects of target-distractor similarity and old age on search, subitization, and counting

Three experiments examined the effects of target-distractor (T-D) similarity and old age on the efficiency of searching for single targets and enumerating multiple targets. Experiment 1 showed that increasing T-D similarity selectively reduced the efficiency of enumerating small (< 4) numerosities (subitizing) but had little effect on enumerating larger numerosities (counting) or searching for a single target. Experiment 2 provided converging evidence using fixation frequencies and a finer range of T-D similarities. Experiment 3 showed that T-D similarity had a greater impact on older than on young adults, but only for subitizing. The data are discussed in terms of the mechanisms and architecture of early visual tagging, dissociable effects in search and enumeration, and the effects of aging on visual processing.     

An investigation into some of the underlying associative verbal processes of the stroop colour effect

The Stroop test was examined to throw some light on the verbal basis of the test. When words are presented printed in the wrong colour it is found that the written word provides more interference with response to the colour of print than occurs the other way round (the Stroop effect). It was shown that, by allowing subjects to match the colour of the print with colour patches instead of words, the interference due to the written word can be considerably reduced. In a further experiment, associations were formed by the subjects between nonsense syllables and colours in the course of a paired-associate learning task. When nonsense syllables were presented printed in colours different from those associated with them, it was found that the interference effects depended upon the direction of the stimulus-response association in the paired-associate experiment. It is concluded that the underlying processes in the Stroop effect are primarily verbal and depend partly upon the directionality of previously established verbal associations.     

Use of morphology in spelling by children with dyslexia and typically developing children

In English and some other languages, spelling problems that arise at a phonological level can sometimes be solved through consideration of morphology. For example, children could infer that tuned should contain an n and that fighting should contain a t because their stems include these letters. Children could thus avoid misspellings that might otherwise occur, such as "tud" and "fiding." We used a spelling-level match design to examine the extent to which children with dyslexia and younger typical children use morphology in this way. Both groups of children benefited from morphology to some extent, but not as much as they could have given their knowledge of the stems. Our results suggest that the spellings produced by older children with dyslexia are similar to those of younger normal children in their morphological characteristics, as well as in other ways.