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Biomedical subjects

A Henik

Publications and source records attributed to A Henik.

At least 19 recordsLinked to original sources
PubMed2001

Attentional asymmetry in schizophrenia: disengagement and inhibition of return deficits.

This research examined 2 components of visual orienting in medicated schizophrenia patients: the validity effect and the inhibition of return (IOR). In the 1st experiment, patients showed the expected asymmetry in orienting attention, that is, larger validity effect in the right visual field than in the left. However, this asymmetry was due to a deficit in facilitatory processes rather than a disengagement deficit. In addition, patients showed a deficit in IOR. In the 2nd experiment, a 2nd central cue for summoning attention, explicitly, back to the center was used. In this experiment, normal IOR in schizophrenia patients was found. Because it was shown that schizophrenia patients do not have a disengagement deficit, IOR possibly could not be observed because of the increased facilitation in that location. It was proposed that the abnormality in visual attention in schizophrenia is due to a deficit in inhibitory processes.

Adult↗
PubMed2001

Interpreting Stroop interference: an analysis of differences between task versions.

The present study investigated methodological differences between the clinical version of the Stroop Color and Word Test and the computerized single-trial version. Three experiments show that different presentations of the Stroop task can produce different levels of interference. The 1st experiment examined the effect of blocking; the 2nd experiment examined different control conditions. Greater interference in the blocked clinical version appears to result from lower response times (RTs) in the neutral condition, not from greater RTs in the incongruent condition. Experiment 3 examined the impact of shifting attention across locations while responding to Stroop stimuli. The present set of findings sheds light on the inconsistency in the clinical literature and demonstrates that the method and selection of neutral stimuli (that provide the baseline by which interference is measured) are critical because they clearly can change performance.

Adult↗
PubMed2000

Task set switching in schizophrenia.

The authors used a task-switching paradigm to investigate set shifting ability in schizophrenia. This paradigm included 2 choice reaction time (RT) tasks: up-down and right-left. Switching tasks were associated with costs (i.e., longer RT in task-switch trials than in task-repetition trials); patients responded more slowly than controls and suffered greater switching costs, were as efficient as controls in engaging in an upcoming task set, and were faster than controls in disengaging from the previous task set. There were indications that patients quickly forgot what each keypress indicated, making it necessary for them to acquire response meaning information anew in each trial. To test this notion, the authors subsequently tested normal participants in conditions in which response meaning information needed to be acquired anew in each trial. These participants produced a pattern of switching costs resembling that of patients. Results suggest that set switching difficulties in schizophrenia, as exhibited in the present paradigm, reflect poor memory for task context information.

Adult↗
PubMed2000

The endogenous modulation of IOR is nasal-temporal asymmetric.

Inhibition of return (IOR) refers to a reflexive mechanism mediated by phylogenetically primitive extrageniculate visuomotor pathways, which apparently serves to favor novel spatial locations by inhibiting those recently sampled. We demonstrate an asymmetry between temporal and nasal hemifields in the strategic modulation of IOR by endogenously controlled attention. Exogenous and endogenous precues were manipulated independently on each trial such that precues to initiate endogenous spatial orienting were presented after IOR had been activated by exogenous visual signals. Both types of precues manifested their characteristic effects on reaction time (RT) to detect subsequent targets: facilitation by endogenous precues, and IOR by exogenous precues. Under monocular viewing, an asymmetric interaction between these two mechanisms was observed. While endogenous allocation of attention to the nasal hemifield reduced IOR, no endogenous modulation of IOR was present in the temporal hemifield where the effects of the two types of precues were independent. These observations suggest a framework for understanding the neurobiology of automaticity and control - from an evolutionary perspective.

Attention↗
PubMed2000

Stroop effect in words that differ from color words in one letter only.

In two experiments, participants named the color of a colored word, which was a Hebrew color word or a word in Hebrew that was different from a color word in one letter only. The magnitude of the Stroop effect increased with the location of the changed letter. It was smallest when the first letter of the color word was replaced, resulting in a noncolor word, and it was largest when the last letter was replaced. These results challenge the assumption that automatic reading, as indicated by the Stroop effect, can be explained exclusively by memory retrieval accounts of automaticity. The results also have implications for the sources of facilitation and inhibition in the Stroop effect.

Adult↗
PubMed1999

Interactions between color and word processing in a flanker task.

To examine interactions between color and word attributes, participants responded, either manually or vocally, to a central target (color patch or word) flanked by a Stroop stimulus. Color and word attributes of the flanker affected both vocal and manual responding to color patches. Color and word flankers also affected manual responding to word targets, but only word flanker affected vocal responding to word targets. These results are not consistent with models (e.g., translational models) of Stroop tasks, which posit that interactions between colors and words occur only when vocal responding is required.

Adult↗
PubMed1997

Automaticity and consciousness: is perceiving the word necessary for reading it?

Definitions of automaticity imply insensitivity of the Stroop effect to conscious perceiving of the word. Subjects in the Stroop task reported the meaning of the stimulus word (in addition to its color) in 7% of the trials. The magnitude of the Stroop effect in these trials was correlated with subjects' ability to report the stimulus meaning. Furthermore, the effect was absent when subjects failed to report the stimulus meaning. These findings challenge the assumption that automatic processing is unconscious. A distinction between automatic and non-automatic processing in terms of modes of consciousness is discussed.

Attention↗
PubMed1995

Effects of cognitive load on semantic priming in patients with schizophrenia.

Schizophrenic and control participants received 2 blocks of trials in each experiment. In 1 block they were exposed to regular priming trials (doctor-nurse), and in another block a nonlexical probe was presented at prime onset for 40 ms. Regardless of stimulus onset asynchrony (SOA), the schizophrenic patients showed hyperpriming when no distrator was present. Paying attention to the distracting stimulus reduced priming in the patient group irrespective of SOA. Under certain situations, the reduction in priming appeared even when participants were asked to ignore the distracting stimulus. Thus, even a nonsemantic distractor may be detrimental to schizophrenic patients' language processing. That SOA did not modulate the reduction in priming effect is consistent with the suggestion that attentional resources are required even with short prime-target intervals.

Acoustic Stimulation↗
PubMed1994

Capacity demands of automatic processes in semantic priming.

In three experiments, we examined the effects of prime-target stimulus onset asynchrony (SOA) and the proportion of related primes and targets (relatedness proportion, or RP) on semantic priming when the prime was either named or was searched for a specific letter. In Experiment 1, with an RP of .50, priming occurred at SOAs of 240 and 840 msec when the prime was named, but no priming was found at either SOA when the prime was searched for a letter. In Experiment 2 the RP was either .20 or .80, and the SOA was set at 1,700 msec; priming again was found in both conditions when the prime was named, but only in the RP .80 condition when a letter search task was performed on the prime. In Experiment 3, both the proportion of related trials and SOA were varied; as in the previous experiments, no priming effects were found with the letter search task for either SOA in the RP .20 condition, but the priming effect was reinstated in the RP .80 condition. These results are discussed with respect to how limited capacity resources are allocated and how they influence semantic priming effects.

Discrimination, Psychological↗
PubMed1993

Disinhibition of automatic word reading in Parkinson's disease.

The Stroop phenomenon was studied in patients with early and late onset Parkinson's disease (PD) and in normal controls to examine the effect of this disease on generating and controlling automatic mental processes. In the Stroop task subjects are presented with color or neutral words in various colors and asked to ignore the word and name its color as fast as possible. We examined the facilitory and interference effects of the irrelevant word upon naming the color by using computerized version of the Stroop test. Vocal reaction times of both early and late onset PD patients presented an augmented facilitory effect. In addition, error data of the late onset PD patients showed an enlarged interference effect. These effects are related to an impairment in the ability to control automatic-reflexive processes. The augmented facilitory effect is manifest early in the course of PD suggesting that the basal ganglia act to inhibit some automatic cognitive processes. The origin of the interference effect in late onset PD patients is less clear. It may reflect more severe basal ganglia dysfunction; or a decline in cortical inhibitory processes.

Adult↗
PubMed1993

Dissociation of lexical and semantic aspects in word processing.

We present data and review studies that show a dissociation between identity and semantic priming. This dissociation appears as a result of employing certain prime tasks, adding cognitive load or following brain damage. Such a dissociation suggests that while activation of the word's representation is obligatory, the spread of activation to related concepts is not.

Brain Injuries↗
PubMed1992

Controlling Stroop effects by manipulating expectations for color words.

An important characteristic of automatic processing is its uncontrollability. The Stroop phenomenon is regarded as a prototypical example of this characteristic of automatic processing, hence, the Stroop effect should not change when the percentages of color words versus neutral stimuli are manipulated to induce controlled processing. We found that Stroop interference decreased as the percentage of color words increased. Furthermore, the magnitude of the inhibitory component of the Stroop effect was negatively correlated with the percentage of color words; the facilitatory component was insensitive to the manipulation. These results suggest that the Stroop effect is controllable (see Logan, 1980) and that the locus of control is postlexical. The results also suggest that facilitation and inhibition are produced by different mechanisms and challenge those models of the Stroop phenomenon (e.g., Cohen, Dunbar, & McClelland, 1990; Phaf, Van der Heijden, & Hudson, 1990) that assume that a single processing mechanism causes facilitation and inhibition and that control affects facilitation and inhibition alike (Logan, 1980).

Adult↗
PubMed1991

Automatic processes in lexical access and spreading activation.

The semantic priming effect can be reduced or eliminated depending on how the prime word is processed. The experiments reported here investigate this prime task effect. Two experiments used identity and semantic priming tasks to determine whether the prime word is encoded at a lexical level under letter-search conditions. When the prime task was naming, both identity and semantic priming occurred; however, when a letter-search task was performed on the prime word, only identity priming occurred, thus supporting the argument that the search task affects activation of semantic associates rather than lexical access of the prime word. Another experiment demonstrated that this identity priming was the result of lexical processes rather than of letter-by-letter priming. A cross-modal priming technique demonstrated that the letter-search prime task does not actively suppress activation of semantic associates. The implications of these results for automaticity and for proposed mechanisms of priming are discussed.

Adult↗
PubMed1990

Perceived temperamental characteristics and regulation of physiological stress: a study of wheezy babies.

Explored prospectively were the temperamental dimensions involved in the modulation of wheeziness in infancy. Subjects were 69 infants, 4 to 8 months old, referred to the emergency room because of wheeziness, and a control group of 30 infants, 4 to 8 months old, referred to the emergency room because of an acute illness other than wheeziness. Infant respiratory clinical score for wheeziness was registered and the Revised Infant Temperament Questionnaire and a demographic questionnaire were completed. Fourteen months later the recurrence of wheeziness attacks--that is, asthma--was investigated. Maternal reports of infant's rhythmicity significantly improved the prediction of asthma among wheezy babies; wheezy babies were perceived as significantly less active than nonwheezy babies.

Arousal↗
PubMed1990

Performance consequences of two types of stereo picture compression.

Two algorithms for stereo picture compression were evaluated. According to one algorithm, consistent with the fusion theory of depth perception, the reduction of information in the two pictures was about equal. The other algorithm, consistent with the suppression theory of depth perception, was based on very deep compression of one picture and minimal reduction of information in the second picture. Subjects performed depth decisions and object decisions on the compressed picture. They were able to perform both tasks on the compressed pictures, though performance generally was worse than in the un-compressed control conditions. In both tasks performance was better for an uneven division of information between the two pictures. These results are consistent with the suppression theory of depth perception.

Adult↗