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I Czigler

Publications and source records attributed to I Czigler.

31 records · Page 2Linked to original sources
PubMed1991

Event-related potentials in a lexical stroop task.

In a reaction time (RT) situation the subjects made word/non-word decisions to strings of four letters. The original strings could be either words or non-words when read from left to right. Decisions were made for strings resulting when reading the letters in a different sequence specified on each trial. The 'non-word' RT was longer than the 'word' RT, and RT increased further when the (correct) non-word decision was made to strings which constituted a word in the (traditional) left to right order. Event related potentials (ERPs) following the strings were more negative on the left side (the onset of the negativity was approx. 240 ms). Motor reactions were preceded by an epoch (700-300 ms before the response) where the ERPs of trials with stimulus/response conflict were relatively positive. However, the negativity preceding the response (motor potential) appeared to be independent of the stimulus/response conflict. 'Word' responses were preceded and followed by a positive wave, independent of the motor potential. This positivity is considered to be a very late member of the P3 complex related to lexical memory processes.

Adult↗
PubMed1990

Event-related potentials in a visual discrimination task: negative waves related to detection and attention.

Event-related potential effects of deviant stimuli were investigated in a visual discrimination task. The stimuli (two angles within a frame) were either frequent (Standard) or one of two types of infrequent deviant (Deviant 1 or Deviant 2) stimuli. In comparison to the Standard stimuli, for Deviant 1 the two angles differed in their orientation, whereas for Deviant 2 the angles were identical but the frame was thicker. In Condition 1 the subjects counted the number of Deviant 1 stimuli. Of the 13 subjects, 12 did not detect the fact that some of the frames were thicker in this condition (i.e., for the Deviant 2 stimuli in Condition 2). The task in Condition 2 was the same (i.e., the target was Deviant 1), but the subjects were instructed about the thicker frame of Deviant 2 stimuli. In Condition 3, Deviant 2 stimuli became the targets. In comparison to the Standard, Deviant 1 elicited two posterior negative waves in the 120-180 and 240-300 ms latency ranges respectively. In addition, when Deviant 1 was the target stimulus (Conditions 1 and 2), this stimulus elicited the N2 and the P300 as well. In contrast, the irrelevant Deviant 2 elicited no such waves. In the target position (Condition 3), Deviant 2 elicited the second posterior negativity, the N2 and the late positivity. The earlier negativity is considered to be a correlate of processes connected to the automatic detection of the deviant features, whereas the later negativity is considered to be related to attentive processes, i.e., this wave is considered to be a member of the family of processing negativities.

Adult↗
PubMed1989

Event-related potential evidence of semantic mismatch in a 'same-different' reaction time task.

In a 'same-different' reaction time (RT) task, suit (spades and/or hearts) target stimuli, and irrelevant suits (distractors) or plus signs (indifferent elements) were presented. The 'same' RT was shorter than the 'different' RT. This 'fast same' effect was independent of the RT increase caused by the distractor stimuli. Event-related potentials (ERPs) in trials with distractor elements were more negative in the 350-600 ms latency range than the ERPs of trials with different irrelevant elements.

Adult↗
PubMed1988

Selection within fixation: event-related potentials in a visual matching task.

In a visual matching task, suit (spades and/or hearts) target stimuli and irrelevant stimuli (either spade and/or heart suits or plus signs) were presented to a field of 1 deg. The irrelevant stimuli appeared either beside or between the targets. The 'same-different' reaction times (RT) and the event-related potentials were measured. 'Same' RTs were found to be longer in the presence of suit distractors that were different from the target, than in the case of plus-sign irrelevant stimuli and irrelevant stimuli identical to the targets. This effect was larger when the irrelevant stimuli appeared between the targets. 'Different' RTs were longer in the presence of suit distractors and when the irrelevant stimuli were between the targets. In the 'same' trials, the latency of the late positive complex (P300) was larger in the suit distractor conditions, but this effect was unrelated to the target localization factor. Thus, the P300 latency seems to be related to the complexity of the stimulus display and thus to the difficulty of input processing. Concerning the earlier latency range, in the conditions with short RT, a latent negative shift (with 170 ms peak latency) was detected when these responses were compared to conditions of longer RT.

Adult↗
PubMed1983

The effect of selective attention on pattern-specific visual evoked potentials.

In a complex choice reaction time experiment, patterned stimuli without luminance change were presented, and pattern-specific visual evoked potentials to lower half-field stimulation were recorded. Two experimental conditions were used. The first was the between-field selection, where square patterns were presented in either the lower or the upper half of the visual field. In a given stimulus run one of the half-fields was task-relevant, and the subjects' task was to press a microswitch to stimuli of higher duration value (GO stimuli), while they had to ignore shorter ones, i. e. stimuli of lower apparent spatial contrast (NOGO stimuli). They had to ignore the stimuli appearing in the irrelevant half-field (IRR stimuli). In order to ensure proper fixation, the subjects had to press another microswitch at the onset of a dim light at the fixation point (CRT stimuli). Our second experimental condition was the within-field selection, where the GO, NOGO, and IRR stimuli appeared in the lower half of the visual field. GO and NOGO were square patterns while IRR stimuli were constructed of circles, or vice versa. (The CRT stimuli were the same as in the previous condition.) Three pattern-specific visual evoked potential components were identified, i. e. CI (70 ms latency), CII (100 ms latency), and CIII (170 ms latency). There were marked selective attention effects on both the CI-CII and CII-CIII peak-to-peak amplitudes. In both experimental conditions, responses with the highest amplitude were evoked by the GO type of stimuli, while the IRR stimuli evoked the smallest responses. According to these results, attention effects on the pattern-specific visual evoked potentials in the first 200 ms cannot be attributed to a simple stimulus set kind of selection.

Adolescent↗
PubMed1979

Effects of the inter-stimulus interval on visual evoked potentials to patterned stimuli.

Visual evoked potentials to patterned stimulation of the upper and lower half of the visual field were investigated in nine adult Ss. The inter-stimulus interval varied between 350 and 2,600 msec. With patterned stimulation, no inter-stimulus interval effects were obtained for occipital components. In contrast for the vertex lead, on the other hand, as inter-stimulus interval increased, the N140-P200 amplitude increased. Because of the heterogeneity subjects' responses evoked by upper half-field stimulation, this effect was more pronounced in lower half-field stimulation.

Adult↗
PubMedDate not supplied

Event-related potential correlates of color selection and lexical decision: hierarchical processing or late selection?

In a series of experiments, a color discrimination task was combined with a lexical decision task. Words and non-words that appeared in the relevant color elicited attention-related event-related potential (ERP) components (anterior positivity, posterior N2 and N2b). The results of the recognition tasks, that investigated the retention of the words, were not closely related to the emergence of these ERP components. These findings show that instead of being the correlates of a filtering mechanism confining lexical processing to stimuli in relevant color, the attention-related ERP components are correlates of late selection processes, ensuring task-related stimulus evaluation.

Adult↗
PubMedDate not supplied

Age, color processing and meaningfulness: an event-related potential study.

The effects of aging on event-related potentials (ERPs) and reaction time (RT) performance were investigated in a task that combined color discrimination and lexical decision. The stimuli were either words or non-words, presented either in the relevant or in the irrelevant color. RT responses were required to words in the relevant color. Stimuli appeared in the relevant color elicited attention-related ERP components (anterior positivity, selection negativity and N2b). The latency values of the attention-related ERP components and the RT were longer in the older group, indicating the slowing down of attentional processes in the elderly. In the older group the late positivity to stimuli in the relevant color was absent over the posterior locations. Unlike in the older group, in the younger subjects the words appeared in the irrelevant color elicited a central negative wave in the 400 ms range. These results are considered as a capacity limitation in the elderly in processing of the stimulus characteristics beyond to the actual stimulus-response contingencies.

Adult↗