Differences between searching among objects and searching among holes

We report results from six experiments in which participants had to search for a "C" among "O" distractors. The search items were either holes or objects, defined by motion, contrast, or both. Our main findings were (1) it was easier to search among objects than to search among holes, and (2) the difference between search among objects and search among holes was primarily caused by grouping with the background. The data support the hypothesis that the shape of a hole is only available indirectly. We further note that, in our experiments, search performance for both holes and objects depended on the surface medium used to define the search items.     

Preview search and contextual cuing

We investigated the effect of contextual cuing (M. M. Chun & Y. Jiang, 1998) within the preview paradigm (D. G. Watson & G. W. Humphreys, 1997). Contextual cuing was shown with a 10-item letter search but not with more crowded 20-item displays. However, contextual learning did occur in a preview procedure in which 10 preview items were followed by 10 new items. Repeating the new items alone did not generate contextual learning, but repeating the preview items alone did, as long as they had a consistent spatial relation with the target. This was not merely due to the onset of the preview items being associated with the target location. No learning effect took place with a preview of homogeneous items that competed less for selection with new stimuli. The results provide evidence for old items being processed in preview search and providing a context for subsequent search of new items.     

Visual search for object orientation can be modulated by canonical orientation

The authors studied the influence of canonical orientation on visual search for object orientation. Displays consisted of pictures of animals whose axis of elongation was either vertical or tilted in their canonical orientation. Target orientation could be either congruent or incongruent with the object's canonical orientation. In Experiment 1, vertical canonical targets were detected faster when they were tilted (incongruent) than when they were vertical (congruent). This search asymmetry was reversed for tilted canonical targets. The effect of canonical orientation was partially preserved when objects were high-pass filtered, but it was eliminated when they were low-pass filtered, rendering them as unfamiliar shapes (Experiment 2). The effect of canonical orientation was also eliminated by inverting the objects (Experiment 3) and in a patient with visual agnosia (Experiment 4). These results indicate that orientation search with familiar objects can be modulated by canonical orientation, and they indicate a top-down influence on orientation processing.     

What is "marked" in visual marking? Evidence for effects of configuration in preview search

Visual search for a conjunction target is facilitated when distractor sets are segmented over time: the preview benefit Watson and Humphreys (1997) suggested that this benefit involved inhibition of old items (visual marking, VM). We investigated whether the preview benefit is sensitive to the configuration of the old distractors. Old distractors changed their location prior to the occurrence of the new items, while also either changing or maintaining their configuration. Configuration changes disrupted search. The results are consistent with object-based VM, which is sensitive to the configuration of old stimuli.     

Motor facilitation following action observation: a behavioural study in prehensile action

Previous research has shown that the observation of actions and the execution of actions activate common neural systems. More recently, we have presented data showing that action observation of prehension primes subsequent execution (Castiello, Lusher, Mari, Edwards, & Humphreys, 2002). In the current paper we examined action priming under conditions in which the size of the prime did not predict the size of the target (only 20% of trials were valid). We demonstrated reliable priming under these conditions, consistent with the effect occurring automatically. In addition, we show priming even when observers saw just the object rather than the object and a reaching action on the prime trial. We discuss the findings in relation to the role of mirror neurons and object affordances.     

What you get out of memory depends on the question you ask

Following study, participants received 2 tests. The 1st was a recognition test; the 2nd was designed to tap recollection. The objective was to examine performance on Test 1 conditional on Test 2 performance. In Experiment 1, contrary to process dissociation assumptions, exclusion errors better predicted subsequent recollection than did inclusion errors. In Experiments 2 and 3, with alternate questions posed on Test 2, words having high estimates of recollection with one question had high estimates of familiarity with the other question. Results supported the following: (a) the 2-test procedure has considerable potential for elucidating the relationship between recollection and familiarity; (b) there is substantial evidence for dependency between such processes when estimates are obtained using the process dissociation and remember-know procedures; and (c) order of information access appears to depend on the question posed to the memory system.     

Emotional cues do not increase the likelihood of tip-of-the-tongue states

In a recent article, Schwartz (Psychonomic Bulletin & Review 17:82?C87, 2010) reported the effects of emotion on tip-of-the-tongue states (TOTs). He found increased TOTs for emotion-inducing questions, as well as a carryover effect in which high TOT rates were observed following emotion-inducing questions. In the present study, we sought to replicate these findings while controlling for word frequency, but we found an increased TOT rate neither for emotion-inducing questions nor following emotion-inducing questions. We report three attempts to replicate Schwartz??s (Psychonomic Bulletin & Review 17:82?C87, 2010) effect that focused on systematic differences in word frequency between stimulus sets in the original study; none of the key findings reported by Schwartz (Psychonomic Bulletin & Review 17:82?C87, 2010) were found in any of the experiments. These results fail to support prior claims concerning the effects of emotion on TOTs Schwartz (Psychonomic Bulletin & Review 17:82?C87, 2010). The discussion focuses on the importance of controlling for systematic differences in word characteristics between groups of items.     

Dopamine, working memory, and training induced plasticity: implications for developmental research

Cognitive deficits and particularly deficits in working memory (WM) capacity are common features in neuropsychiatric disorders. Understanding the underlying mechanisms through which WM capacity can be improved is therefore of great importance. Several lines of research indicate that dopamine plays an important role not only in WM function but also for improving WM capacity. For example, pharmacological interventions acting on the dopaminergic system, such as methylphenidate, improve WM performance. In addition, behavioral interventions for improving WM performance in the form of intensive computerized training have recently been associated with changes in dopamine receptor density. These two different means of improving WM performance--pharmacological and behavioral--are thus associated with similar biological mechanisms in the brain involving dopaminergic systems. This article reviews some of the evidence for the role of dopamine in WM functioning, in particular concerning the link to WM development and cognitive plasticity. Novel data are presented showing that variation in the dopamine transporter gene (DAT1) influences improvements in WM and fluid intelligence in preschool-age children following cognitive training. Our results emphasize the importance of the role of dopamine in determining cognitive plasticity.     

Flexible feature-based inhibition in visual search mediates magnified impairments of selection: evidence from carry-over effects under dynamic preview-search conditions

Evidence for inhibitory processes in visual search comes from studies using preview conditions, where responses to new targets are delayed if they carry a featural attribute belonging to the old distractor items that are currently being ignored-the negative carry-over effect (Braithwaite, Humphreys, & Hodsoll, 2003). We examined whether inhibition was applied in the same manner across different types of displays or whether the inhibitory weighting applied to different features varied with their utility for the search task. To test this, we present the first empirical investigation of negative carry-over effects under the ecologically valid conditions of dynamic visual search. Experiment 1 investigated preview search using dynamic moving and static displays. Detection was very poor when new targets carried the color of the old distractors, and this negative carry-over effect was significantly exaggerated with moving, compared with static, displays. Experiments 2a and 2b demonstrated that this effect could not be attributed to an increased role of preattentive grouping between new and old items for dynamic displays. Collectively, the findings suggest that feature-based inhibition contributes strongly to preview search through dynamic displays, and this leads to an amplified attentional blindness to new targets. The data specifically indicate that inhibitory processes in search differentially weight color and location in moving and static displays, and that feature-based inhibition may underlie many instances of sustained inattentional blindness in everyday life.