Biomedical subjects

Tracy L Taylor

Publications and source records attributed to Tracy L Taylor.

8 recordsLinked to original sources

PubMed2006

Influence of history on saccade countermanding performance in humans and macaque monkeys.

The stop-signal or countermanding task probes the ability to control action by requiring subjects to withhold a planned movement in response to an infrequent stop signal which they do with variable success depending on the delay of the stop signal. We investigated whether performance of humans and macaque monkeys in a saccade countermanding task was influenced by stimulus and performance history. In spite of idiosyncrasies across subjects several trends were evident in both humans and monkeys. Response time decreased after successive trials with no stop signal. Response time increased after successive trials with a stop signal. However, post-error slowing was not observed. Increased response time was observed mainly or only after cancelled (signal inhibit) trials and not after noncancelled (signal respond) trials. These global trends were based on rapid adjustments of response time in response to momentary fluctuations in the fraction of stop signal trials. The effects of trial sequence on the probability of responding were weaker and more idiosyncratic across subjects when stop signal fraction was fixed. However, both response time and probability of responding were influenced strongly by variations in the fraction of stop signal trials. These results indicate that the race model of countermanding performance requires extension to account for these sequential dependencies and provide a basis for physiological studies of executive control of countermanding saccade performance.

Animals↗

PubMed2006

Inhibition of return for expected and unexpected targets.

Inhibition of return (IOR) refers to slower reaction times (RTs) to targets that occur in the same, rather than in a different, location as a preceding onset cue. The present study examined IOR for expected (likely) and unexpected (unlikely) targets under conditions in which stimulus-response (S-R) expectancies were generated on a trial-by-trial basis or maintained across a block of trials. Three boxes were aligned along the vertical midline. In Experiments 1 and 2, the appearance of a cue in the upper or lower box was a signal to generate an expectancy about the most likely color of an impending discrimination target. In Experiment 3, one target color was more likely than another across a block of trials. In all cases, cue location did not predict target location. When S-R expectancies were generated on a trial-by-trial basis, IOR occurred for Unlikely targets but not for Likely targets; this was true across a range of cue-target stimulus onset asynchronies. In contrast, when S-R expectancies were maintained over a block of trials, IOR was larger for Likely than for Unlikely targets. These findings reveal a critical interaction of S-R expectancies with IOR. This interaction not only demonstrates the modulation of IOR by cognitive expectancies, but in doing so also provides evidence that is consistent with the view that IOR reflects a conservative response bias.

Attention↗

PubMed2006

Cease remembering: control processes in directed forgetting.

On the premise that committing a word to memory is a type of covert action capable of being stopped, this study merged an item-method directed forgetting paradigm with a stop signal paradigm. The primary dependent measure was immediate recall. Indicating that participants were able to countermand the default instruction to remember, there was an overall directed forgetting effect, the magnitude of which varied as a function of forget signal delay. The results suggest that the covert act of intentionally forgetting may engage cognitive control processes at encoding that are analogous to those required to prevent the execution of prepotent overt responses.

Analysis of Variance↗

PubMed2005

Inhibition of return and repetition priming effects in localization and discrimination tasks.

Inhibition of return (IOR) refers to slower responding to a stimulus that is presented at the same, rather than a different location as a preceding, spatially nonpredictive, stimulus. Repetition priming refers to speeded responding to a stimulus that duplicates the visual characteristics of a stimulus that precedes it. IOR and repetition priming effects interact in nonspatial discrimination tasks but not in localization tasks; three experiments examined whether this is due to processing differences or due to response differences between tasks. Two stimuli, S1 and S2, occurred on each trial. In Experiment 1, S1 and S2 were both peripheral arrows; in Experiment 2, S1 was a central arrow and S2 was a peripheral nondirectional rectangle; in Experiment 3, S1 was a peripheral nondirectional rectangle and S2 was a peripheral arrow. S1 never required a response; S2 required a localization or a discrimination response. Despite evidence that form information was likely extracted from the arrow stimuli, the localization task revealed no repetition priming: IOR occurred regardless of shared visual identity of the S1 and S2 arrows. The discrimination task revealed IOR only when the visual identity changed from S1 to S2; otherwise, facilitation occurred. These results suggest that IOR is masked by repetition priming only when the response depends on the explicit processing of form information; repetition priming does not occur when such information is extracted automatically but is task (and response) irrelevant.

Adolescent↗

PubMed2005

Inhibition of return following instructions to remember and forget.

Inhibition of return (IOR) refers to slowed responding to a target that appears in the same rather than in a different location as a preceding peripheral onset cue. This study examined IOR as a function of whether the peripheral onset cue was a word that participants were directed to remember or forget. Using a modified item-method directed forgetting paradigm, words appeared one at a time to the left or right, followed by a remember or forget instruction. A target dot was then presented either in the same peripheral location as the preceding word or in a different location; participants made a speeded response to localize this target. Confirming compliance with the memory instructions, recall tests that alternated with blocks of IOR trials (Experiment 1) revealed few intrusions of to-be-forgotten words, and a final recognition test (Experiments 1 and 3) revealed more hits for to-be-remembered words than for to-be-forgotten words. Reaction times to the target dot revealed greater magnitude IOR following to-be-forgotten words than following to-be-remembered words (Experiments 1 and 3). Moreover, when compared to baseline IOR values (Experiment 2), it appeared that this difference resulted from a magnification of IOR following forget instructions and a reduction in IOR following remember instructions. These results demonstrate the usefulness of IOR as an index of memorial processes and suggest that attentional orienting may play a role in the remembering and forgetting of words presented in peripheral visual locations.

Attention↗

PubMed2005

Inhibition of return for faces.

Inhibition of return (IOR) refers to slower reaction times when a target appears unpredictably in the same location as a preceding cue, rather than in a different location. In the present study, frontal images of human faces were presented intact as face configurations, were rearranged to produce scrambled-face configurations, or were pixilated and randomized to produce nonface configurations. In an orienting paradigm designed to elicit IOR, face and scrambled-face stimuli were used as cues (Experiment 1), as targets (Experiment 2), or along with pixilated nonface stimuli as both cues and targets (Experiment 3). The magnitude of IOR for subsequent localization targets was unaffected by cue configuration. Likewise, the magnitude of IOR was unaffected by target configuration. These results suggest that IOR is a "blind" mechanism that is unaffected by the mere occurrence of biologically relevant cue and target stimuli.

Cues↗

PubMed2003

The interplay of stop signal inhibition and inhibition of return.

Inhibition of return (IOR) refers to slower responding to a stimulus that appears in the same rather than a different location as that of a preceding stimulus. The goal of the present study was to examine the relationship between IOR and stop signal inhibition. Participants were presented with two stimuli (S1 and S2) on each trial. On half of the trials (go trials), participants were required to make a speeded button-press response to report the location of S1; on the other half of trials (stop trials), they were required to cancel the response to S1, as indicated by the appearance of a stop signal at a variable delay (stop signal delay, SSD) after the appearance of S1. Success in cancelling an S1 response varied directly as a function of the SSD: The longer the delay, the more difficult it was for participants to cancel the prepared response. We examined the magnitude of IOR in the S2 reaction times as a function of whether participants made a correct go response to S1, made an erroneous non-cancelled response to S1, or successfully cancelled a response to S1. Our results indicated that the presentation of a stop signal increased the magnitude of IOR, even when the S1 response was not successfully cancelled. However, this was true only when the to-be-cancelled response involved the same effectors as the response used to reveal IOR. These results suggest that there may be a motor component to IOR that is sensitive to the same inhibitory processes that are used to cancel responses in a stop signal paradigm.

Adult↗

PubMed2002

Inhibition of return for target discriminations: the effect of repeating discriminated and irrelevant stimulus dimensions.

Inhibition of return (IOR) refers to slowed reaction times when a target repeats in the same location as a preceding stimulus. In four experiments, the participants were presented with two successive stimuli, S1 and S2. In Experiments 1 and 2, the participants made a speeded discrimination of the identity or orientation of both S1 and S2 (Experiment 1) or of S2 only (Experiment 2). An IOR effect occurred for the repetition of stimulus location, but a facilitatory effect occurred if the stimulus remained unchanged or if an overt response was repeated. In Experiments 3 and 4, the participants localized S1 and S2 (Experiment 3) or S2 only (Experiment 4) to the left or right of center. In this case, repeating the same stimulus had no effect: IOR occurred any time stimulus location repeated. These results demonstrate that the expression of IOR is modulated by the repetition of a target object, but only when the task requires the discrimination of that object; when no discrimination is required, IOR is unaffected.

Adult↗