Biomedical subjects

Daniel N Bub

Publications and source records attributed to Daniel N Bub.

6 recordsLinked to original sources

PubMed2006

Cognitive control in children: stroop interference and suppression of word reading.

The development of cognitive control and its relation to overcoming Stroop interference was assessed in a sample (N= 65) of elementary-school children. Subjects alternately performed Stroop color-naming trials and word-reading trials. In separate blocks, the colored Stroop items were non-color words (incongruent condition) or rows of asterisks (neutral condition). Younger children showed both larger Stroop interference in error rates and a greater slowing of word reading in the incongruent condition compared with older children. We conducted analyses of response time distributions that assessed the degree of word-reading suppression applied by younger and older children. Surprisingly, these analyses indicated that younger children engaged in stronger suppression than older children. We propose that greater Stroop interference among younger children is not due to lack of ability to suppress word reading, but instead is the result of a failure to consistently maintain the task set of color naming.

Child↗

PubMed2006

Perceptual expertise effects are not all or none: spatially limited perceptual expertise for faces in a case of prosopagnosia.

We document a seemingly unique case of severe prosopagnosia, L. R., who suffered damage to his anterior and inferior right temporal lobe as a result of a motor vehicle accident. We systematically investigated each of three factors associated with expert face recognition: fine-level discrimination, holistic processing, and configural processing (Experiments 1-3). Surprisingly, L. R. shows preservation of all three of these processes; that is, his performance in these experiments is comparable to that of normal controls. However, L. R. is only able to apply these processes over a limited spatial extent to the fine-level detail within faces. Thus, when the location of a given change is unpredictable (Experiment 3), L. R. exhibits normal detection of features and spatial configurations only for the lower half of each face. Similarly, when required to divide his attention over multiple face features, L. R. is able to determine the identity of only a single feature (Experiment 4). We discuss these results in the context of forming a better understanding of prosopagnosia and the mechanisms used in face recognition and visual expertise. We conclude that these mechanisms are not "all-or-none," but rather can be impaired incrementally, such that they may remain functional over a restricted spatial area. This conclusion is consistent with previous research suggesting that perceptual expertise is acquired in a spatially incremental manner [Gauthier, I., & Tarr, M. J. Unraveling mechanisms for expert object recognition: Bridging brain activity and behavior. Journal of Experimental Psychology: Human Perception & Performance, 28, 431-446, 2002].

Accidents, Traffic↗

PubMed2004

Category specificity in normal episodic learning: applications to object recognition and category-specific agnosia.

Studies of patients with category-specific agnosia (CSA) have given rise to multiple theories of object recognition, most of which assume the existence of a stable, abstract semantic memory system. We applied an episodic view of memory to questions raised by CSA in a series of studies examining normal observers' recall of newly learned attributes of familiar objects. Subjects first learned to associate arbitrarily assigned colors or textures to objects in a training phase, and then attempted to report the newly learned attribute of each object in a recall task. Our subjects' pattern of recall errors was similar both quantitatively and qualitatively to the identification deficits among patients with CSA for biological objects. Furthermore, errors tended to reflect conceptually and structurally based confusions. We suggest that object identification involves recruitment and integration of information across distributed episodic memories and that this process is susceptible to interference from objects that are structurally similar and conceptually related.

Agnosia↗

PubMed2003

Modulation of word-reading processes in task switching.

The authors examined modulation of the simple act of word naming induced by the conflict arising when that task competes with color naming in a task-switching paradigm. Subjects alternated between naming a word printed in black and naming the color of a stimulus in 2 conditions. In the incongruent condition, the colored stimulus was an irrelevant word generating conflict, and in the neutral condition, color was carried by a row of asterisks. Subjects took substantially longer to name a word printed in black in the incongruent condition, implying a form of suppression. This modulation of the word-naming response was adaptive in that it led to more efficient color naming. The modulation effect was replicated using phoneme detection instead of word naming but not with lexical decision or visual comparison, implicating a phonological encoding process.

Adult↗

PubMed2003

Gesturing and naming: the use of functional knowledge in object identification.

Studies using functional imaging show reliable activation of premotor cortex when observers view manipulable objects. This result has led to the view that knowledge of object function, particularly the actions associated with the typical use of objects, may play a causal role in object identification. To obtain relevant evidence regarding this causal role, we asked subjects to learn gesture-color associations and then attempt to identify objects presented in colors denoting functional gestures that were congruent or incongruent with the objects' use. A strong congruency effect was observed when subjects gestured the use of an object, but not when they named an object. We conclude that our procedure constitutes a sensitive measure of the recruitment and causal role of functional knowledge and that this recruitment is not present during object naming. Preliminary evidence, however, indicates that gestures evoked by the volumetric shape of an object do contribute to object naming.

Adult↗

PubMed2002

Task switching deficits associated with Parkinson's disease reflect depleted attentional resources.

Using a Stroop task switching paradigm, Brown and Marsden [Brain 111 (1988) 323; Brain 114 (1991) 215] proposed that set shifting deficits in Parkinson's disease (PD) reflect limited attentional resources rather than deficits in internal control, as was previously supposed. In the present study, we tested this claim using a more recently developed Stroop task switching paradigm for which the internal control and attentional resources accounts made contrasting predictions. A PD group (N=30) was compared with an age-matched control group (N=34) on vocal response time (RT) for color naming and word reading in response to neutral and incongruent Stroop stimuli. Participants carried out four blocks of task repetition trials, and eight blocks of task switching trials. The results revealed that a deficit due to PD was absent for two conditions necessitating internal control, but was present in the condition which placed the highest demand on attentional resources. This selective deficit is congruent with Brown and Marsden's conclusions that depleted attentional resources, not an impairment in internal control per se, is the basis of the set shifting deficits associated with PD.

Aged↗