Additional-singleton interference in efficient visual search: A common salience route for detection and compound tasks

In efficient search for feature singleton targets, additional singletons (ASs) defined in a nontarget dimension are frequently found to interfere with performance. All search tasks that are processed via a spatial saliency map of the display would be predicted to be subject to such AS interference. In contrast, dual-route models, such as feature integration theory, assume that singletons are detected not via a saliency map, but via a nonspatial route that is immune to interference from cross-dimensional ASs. Consistent with this, a number of studies have reported absent interference effects in detection tasks. However, recent work suggests that the failure to find such effects may be due to the particular frequencies at which ASs were presented, as well as to their relative saliency. These two factors were examined in the present study. In contrast to previous reports, cross-dimensional ASs were found to slow detection (target-present and target-absent) responses, modulated by both their frequency of occurrence and saliency (relative to the target). These findings challenge dual-route models and support single-route models, such as dimension weighting and guided search.     

Voice Onset Time in Ataxic Dysarthria

In eight patients with a purely ataxic syndrome due to cerebellar atrophy the voice onset time (VOT) of word-initial stop consonants was measured at the acoustic signal. The subjects had been asked to produce sentence utterances including either one of the German minimal pair cognates “Daten” (/datn/, “data”) and “Taten” (/tatn/, “deeds”). In addition, a master tape comprising the target words from patients and controls in randomized order was played to six listeners for perceptual evaluation. Two major findings emerged. First, the cerebellar subjects presented with a reduced categorical distinction of the VOT of voiced and unvoiced stop consonants. Second, the patients' target words with initial unvoiced plosive gave rise to a significantly increased number of misassignments at perceptual evaluation. To some extent comparable VOT disruptions have been noted in apraxia of speech and basal ganglia disorders. Thus, different pathomechanisms might result in similar VOT abnormalities.     

An experimental study of social performance and delay on the testimonial validity of story recall

Sixty adults from the city of Linz took part in this experiment. They read a story—The War of the Ghosts—in pairs, and were required to reproduce it either jointly, in dyads, or singly, and either immediately following or one week later. In addition they were asked a number of specific questions about the story, and gave various ratings of confidence and completeness. As predicted, social (dyadic) performance increased confidence, completeness and the incidence of implicational errors (errors which do not contradict the original). Delay significantly diminished confidence. Analyses of confidence for right and wrong answers indicated that subjective testimonial validity was substantial in all conditions. Analyses of objective testimonial validity showed that dyads are more trustworthy than individuals when they are correct, but are less trustworthy when they happen to be wrong. They overall conjidence I accuracy correlation across conditions of +0.6 masks the fact that the greatest obstacle to valid testimony is inappropriate confidence in wrong answers, especially in dyads, and especially immediately after the event. The incidence of implicational errors was highly related positively to measures of confidence and accuracy, whereas confusional errors were independent. Implicational errors are regarded as an especially important element in schematic recall, and are an important aspect of the superiority of social performance.     

Effects of bonuses for punctuality on the tardiness of industrial workers

This study evaluated the effectiveness of an incentive procedure designed to increase the punctuality of six workers who were chronically late to work in a manufacturing company. The six workers in the experiment received a 2.00 pesos ($0.16 U.S.) bonus for every day that they arrived on time. A reversal design was used. The contingent bonuses increased the workers' rates of punctuality compared to their baseline rates. A control group of six workers observed during the same 77-week period showed a trend toward decreasing punctuality. These results suggest that the use of small daily bonuses is a practical procedure for modifying chronic tardiness among industrial workers.     

Dynamismus und atomismus-die beiden systeme der physik in der 1. H?lfte des 19. Jahrhunderts

Ohne ZusammenfassungVortrag beim Kolloquium Zur Struktur und Entwicklung naturwissenschaftlicher Theorien am 23. November 1975 in München.     

Visual search for size-defined target objects is modulated by the Ebbinghaus apparent-size illusion: facilitatory and inhibitory effects of the context objects

Five experiments were carried out to investigate under which conditions the apparent size of objects is computed and exploited optimally in visual search for size-defined targets. Observers searched for a target test circle that was retinally larger than the distractor test circles, with both types of circles surrounded by context circles modulating the apparent size of the test circles (Ebbinghaus illusion). RTs were the faster the better test circles could be differentiated from the context circles, ie with smaller numbers of context circles, larger distances, and higher lightness (or colour) contrast between test and context circles. Apparent-size modulation had a strong influence on search RTs, resulting in faster RTs with smaller, and slower RTs with larger, context circles. A model assuming overall facilitatory effects of the apparent-size modulation and interference effects arising from decreasing test-context circle discriminability can explain the present results.     

Cross-trial priming in visual search for singleton conjunction targets: role of repeated target and distractor features

Kristjánsson, Wang, and Nakayama (2002) demonstrated that visual search for conjunctively defined targets can be substantially expedited ("primed") when target and distractor features are repeated on consecutive trials. Two experiments were conducted to examine whether the search response time (RT) facilitation on target-present trials results from repetition of target-defining features, distractor features, or both. The experiments used a multiple conjunctive search paradigm (adapted from Kristjánsson et al., 2002), in which the target and distractor features were varied (i.e., repeated) independently of each other across successive trials. The RT facilitation was numerically largest when both target and distractor features were repeated, but not significantly larger than that when only distractor features were repeated. This indicates that cross-trial priming effects in conjunctive visual search result mainly from the repetition of distractor, rather than target, features.