Biomedical subjects

Ulrich Ansorge

Publications and source records attributed to Ulrich Ansorge.

15 recordsLinked to original sources

PubMed2006

Preceding stimulus awareness augments offset-evoked potentials: evidence from motion-induced blindness.

Event-related potentials (ERPs) were measured in response to the objective offset of a visual disk under two physically similar conditions: (1) visible conditions in which the target disk was well perceived and (2) invisible conditions in which participants reported to have not seen the target because of motion-induced blindness (Bonneh, Cooperman, & Sagi in Nature 411:798-801, 2001). Electrophysiological responses to the physical offset of the target disk were almost completely absent in the invisible conditions (Experiment 2). In the same conditions, the physical offset was almost completely invisible (Experiment 1). Results suggest an augmenting function of prior awareness of a stimulus for the offset-triggered ERP of that stimulus.

Adult↗

PubMed2005

Latency facilitation in temporal-order judgments: time course of facilitation as a function of judgment type.

The paper is concerned with two models of early visual processing which predict that priming of a visual mask by a preceding masked stimulus speeds up conscious perception of the mask (perceptual latency priming). One model ascribes this speed-up to facilitation by visuo-spatial attention [Scharlau, I., & Neumann, O. (2003a). Perceptual latency priming by masked and unmasked stimuli: Evidence for an attentional explanation. Psychological Research 67, 184-197], the other attributes it to nonspecific upgrading mediated by retino-thalamic and thalamo-cortical pathways [Bachmann, T. (1994). Psychophysiology of visual masking: The fine structure of conscious experience. Commack, NY: Nova Science Publishers]. The models make different predictions about the time course of perceptual latency priming. Four experiments test these predictions. The results provide more support for the attentional than for the upgrading model. The experiments further demonstrate that testing latency facilitation with temporal-order judgments may induce a methodological problem resulting in fairly low estimates. A method which provides a more exhaustive measure is suggested and tested.

Adult↗

PubMed2005

Top-down contingent capture by color: evidence from RT distribution analyses in a manual choice reaction task.

According to the contingent capture hypothesis, observers can specify their control settings in advance of the target's presentation to quickly attend to relevant target colors. Two predictions were derived from this hypothesis and tested in a manual choice response task. First, contingent capture by color was expected: capture of spatial attention by a better-matching color stimulus should be stronger than capture by a less-matching color stimulus. Second, with the control settings specified in advance, the contingent capture by color should commence early after the stimulus onset and should be evident among fast correct responses in an RT distribution. Both predictions are shown to hold true in two experiments. Results are discussed in light of contrasting evidence for saccadic instead of manual responses.

Adult↗

PubMed2005

Intentions determine the effect of invisible metacontrast-masked primes: evidence for top-down contingencies in a peripheral cuing task.

In 5 experiments, the authors tested whether the processing of nonconscious spatial stimulus information depends on a prior intention. This test was conducted with the metacontrast dissociation paradigm. Experiment 1 demonstrated that masked primes that could not be discriminated above chance level affected responses to the visible stimuli that masked them. Experiments 2 and 3 showed that this effect was abolished when the task instruction was changed in such a way that the primes ceased to be task relevant. Experiments 4 and 5 demonstrated that a prime's effect depended on whether it was associated with the same response as the target or with an opposite response.

Adult↗

PubMed2005

Exploring trial-by-trial modulations of the Simon effect.

The present study investigates sequential modulations of the Simon effect. The Simon effect involves faster responses to spatially corresponding than to noncorresponding stimuli, even when stimulus position is irrelevant. Recently, the Simon effect has been shown to decrease or to disappear after noncorresponding predecessor trials. Possible explanations for these sequential modulations include (a) the gating of position-based response activation (conflict monitoring), (b) repetition or alternation effects, and (c) the interaction between feature integration (binding) processes and stimulus-response (S-R) correspondence. Three experiments tested different predictions of these models by comparing Simon effects after neutral trials with those after corresponding and noncorresponding trials, respectively, and by varying the stimulus-onset asynchrony (SOA) between and within experiments. Experiments 1 and 2 revealed large Simon effects after corresponding trials, intermediate Simon effects after neutral trials, and small (or no) Simon effects after noncorresponding trials. Moreover, some systematic effects of S-R repetitions and S-R alternations were observed. Finally, the sequential modulations were maximal at short SOAs and decreased with increasing SOA, but still occurred at an SOA of 6 seconds. The results seem to exclude repetition or alternation effects as the main cause of sequential modulations of the Simon effect, but both conflict monitoring and binding may contribute to these effects.

Adolescent↗

PubMed2004

Visual search for a motion singleton among coherently moving distractors.

In the current study, we tested whether search for a visual motion singleton presented among several coherently moving distractors can be more efficient than search for a motion stimulus presented with a single distractor. Under a variety of conditions, multiple spatially distributed and coherently moving distractors facilitated search for a uniquely moving target relative to a single-motion-distractor condition (Experiments 1, 3, and 4). Color coherencies among static distractors were not equally effective (Experiments 1 and 2). These results confirm that humans are highly sensitive to antagonistically directed motion signals in backgrounds compared with spatially more confined regions of visual images.

Adult↗

PubMed2004

Peripheral cuing by abrupt-onset cues: the influence of color in S-R corresponding conditions.

Research on visuospatial attention indicates that a peripheral abrupt-onset cue at target position (valid condition) facilitates processing of the target, whereas a cue at another position interferes. This validity effect seems to be contingent on a similarity of the cue's color to the set of target colors (cf. J. Exp. Psychol.: Human Percep. Perform. 18 (1992) 1030). In Experiments 1-3, we confirm this contingency with cues that have the potential to activate responses. Thus, attentional capture and response capture are apparently governed by the same principle. In Experiment 2, it is demonstrated that color priming is not responsible for the contingency. In Experiment 3, it is shown that a more efficient reallocation of attention after color-dissimilar cues than after color-similar cues might contribute to the contingency.

Adult↗

PubMed2004

A response-discrimination account of the Simon effect.

Simon effects might partly reflect stimulus-triggered response activation. According to the response-discrimination hypothesis, however, stimulus-triggered response activation shows up in Simon effects only when stimulus locations match the top-down selected spatial codes used to discriminate between alternative responses. Five experiments support this hypothesis. In Experiment 1, spatial codes of each response differed by horizontal and vertical axis position, yet one axis discriminated between alternative responses, whereas the other did not. Simon effects resulted for targets on discriminating axes only. In Experiment 2, both spatial axes discriminated between responses, and targets on both axes produced Simon effects. In Experiment 3, Simon effects resulted for a spatial choice-reaction task but not for a go/no-go task. Even in the go/no-go task, a Simon effect was restored when a two-choice reaction task preceded the go/no-go task (Experiment 4) or when participants initiated trials with responses spatially discriminated from the go response (Experiment 5).

Adult↗

PubMed2004

Top-down contingencies of nonconscious priming revealed by dual-task interference.

According to the direct parameter specification (DPS) account, reaction time effects of invisible primes depend on top-down control settings directed to targets (Neumann & Klotz, 1994). If this hypothesis holds, effects of invisible primes should decrease in dual-task as compared with single-task conditions: Prior to the primes control settings for the alternative task should be activated, which renders a match between target-directed control settings and primes less likely. In Experiments 1-2 and 4-5, a second task interfered with the validity effect of invisible primes. Control conditions ruled out several alternative explanations. Interference was not due to higher spatial memory loads (Experiments 1 vs. 2), increased numbers of stimuli or responses (Experiments 3-5), or increased response latencies (Experiment 3). If predictable, alternative tasks did not interfere (Experiment 3). The results are in line with the DPS account and less so with some classical definitions of automatic processing (e.g., Posner & Snyder, 1975).

Adult↗

PubMed2003

Influences of response-activating stimuli and passage of time on the Simon effect.

Two possible explanations for an interaction between the Simon effect and the flanker-congruence effect (Hommel, 1997) were tested: (1) Direct contributions by the locations of the response-activating flankers to the Simon effect, and (2) the passage of time since the target's onset. In three experiments, little evidence for both explanations was observed. The data confirmed an assumed origin of the Simon effect at the stage of response selection. Further, the results are in line with the assumption that context stimuli contribute indirectly to the Simon effect of the target (i.e., by changing the target's relative position), and extend previous findings to show that the assumption holds for clearly response-activating context stimuli, too. Finally, the results suggest that Simon effects follow different time courses depending on whether they are induced by observer-relative or context-relative target positions.

Adult↗

PubMed2003

Direct parameter specification of an attention shift: evidence from perceptual latency priming.

In the direct parameter specification (DPS) mode of sensorimotor control, response parameters can be specified by stimuli that are not consciously perceived [Psychological Research/Psychologische Forschung 52 (1990) 207]. DPS is contingent on the current intentions. The invisible stimuli can be processed for the purposes of sensorimotor control only if they match the actual intentions, for example, share task-relevant features. The present experiments explore whether attentional capture by masked abrupt-onset stimuli is mediated via DPS. Participants judged which of two visual targets appeared first. Masked primes preceded one of the targets. The primes were either similar to the targets or not, in shape, or in color. Target-like (task-relevant), but not distractor-like (task-irrelevant), primes facilitated perceptual latencies of targets trailing at their positions. Thus, the latency effects resulted from DPS of an attention shift, rather than from bottom-up capture or from top-down search for dynamic features.

Adult↗

PubMed2003

Asymmetric influences of temporally vs. nasally presented masked visual information: evidence for collicular contributions to nonconscious priming effects.

It was tested whether the retino-collicular projection allows for the processing of nonconsciously registered visual information in healthy individuals. Masked primes were presented to different visual hemifields. Because the retino-collicular projection is stronger for temporal than for nasal hemifields, priming should be stronger by temporal than by nasal primes. This pattern was tested in two experiments (Experiments 1 and 3). Further, with less peripheral primes, only available to weaker parts of the retino-collicular projection, hemifield asymmetries of priming vanished (Experiment 2). In conclusion, the study offers first evidence for collicular contributions to nonconscious priming effects by visual information in healthy individuals.

Adult↗

PubMed2003

Top-down contingencies in peripheral cuing: The roles of color and location.

According to contingent-processing accounts, peripheral cuing effects are due to the cues' inadvertent selection for processing by control settings set up for targets (e.g., C. L. Folk, R. W. Remington, & J. C. Johnston, 1992). Consequently, cues similar to targets should have stronger effects than do dissimilar cues. In the current study, this prediction is confirmed for cue-target combinations similar or dissimilar in the static features of color (Experiments 1-3) and location (Experiment 4), even when both cues and targets share the dynamic feature of abrupt onset. Perceptual priming (Experiment 2) and reallocation of attention did not account for similar-dissimilar differences (Experiments 3 and 4). The results are best explained by top-down-contingent attentional effects of the similar cues. Implications for bottom-up accounts of peripheral cuing effects are discussed. ((c) 2003 APA, all rights reserved)

Adult↗

PubMed2002

Spatial intention-response compatibility.

In the current investigation the assumption that intentions and actions are represented in the same medium or code (common coding hypothesis of intention and action) was tested and confirmed [Q. J. Exp. Psychol. 52 (1999) 1; Eur. J. Cognit. Psychol. 9 (1997) 129]. In two experiments it is shown that the intention to produce a spatial consequence in the environment to an otherwise spatially neutral stimulus leads to a shorter response, if the responses and the intended consequences share relative positions compared to a situation where this is not the case. In two control experiments it is ruled out that this spatial intention-response compatibility effect is due to an intention-independent expectancy of the consequences of the correct responses.

Adult↗

PubMed2002

Influences of visibility, intentions, and probability in a peripheral cuing task.

According to the concept of direct parameter specification, nonconsciously registered information can be processed to the extent that it matches currently active intentions of a person. This prediction was tested and confirmed in the current study. Masked visual information provided by peripheral cues led to reaction time (RT) effects only if the information specified one of the required responses (Experiments 1 and 3). Information delivered by the same masked cues that did not match the intentions was not used. However, the same information influenced RT if it was provided by visible cues (Experiments 2 and 3). The results suggest that the processing of nonconsciously registered information is flexible because it is susceptible to the changing intentions of a person. Yet, these processes are apparently restricted, as nonconsciously registered information cannot be used as easily for purposes not corresponding to the currently active intentions as better visible information.

Adult↗