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Arrow cues and other overlearned spatial symbols automatically orient attention according to their spatial meaning. This renders them similar to exogenous cues that occur at stimulus location. Exogenous cues trigger shifts of attention even when they are presented subliminally. Here, we investigate to what extent the mechanisms underlying the orienting of attention by exogenous cues and by arrow cues are comparable by analyzing the effects of visible and masked arrow cues on attention. In Experiment 1, we presented arrow cues with overall 50% validity. Visible cues, but not masked cues, lead to shifts of attention. In Experiment 2, the arrow cues had an overall validity of 80%. Now both visible and masked arrows lead to shifts of attention. This is in line with findings that subliminal exogenous cues capture attention only in a top-down contingent manner, that is, when the cues fit the observer’s intentions.
Our object recognition abilities, a direct product of our experience with objects, are fine-tuned to perfection. Left temporal and lateral areas along the dorsal, action related stream, as well as left infero-temporal areas along the ventral, object related stream are engaged in object recognition. Here we show that expertise modulates the activity of dorsal areas in the recognition of man-made objects with clearly specified functions. Expert chess players were faster than chess novices in identifying chess objects and their functional relations. Experts’ advantage was domain-specific as there were no differences between groups in a control task featuring geometrical shapes. The pattern of eye movements supported the notion that experts’ extensive knowledge about domain objects and their functions enabled superior recognition even when experts were not directly fixating the objects of interest. Functional magnetic resonance imaging (fMRI) related exclusively the areas along the dorsal stream to chess specific object recognition. Besides the commonly involved left temporal and parietal lateral brain areas, we found that only in experts homologous areas on the right hemisphere were also engaged in chess specific object recognition. Based on these results, we discuss whether skilled object recognition does not only involve a more efficient version of the processes found in non-skilled recognition, but also qualitatively different cognitive processes which engage additional brain areas
Alerting signals often serve to reduce temporal uncertainty by predicting the time of stimulus onset. The resulting response time benefits have often been explained by facilitated translation of stimulus codes into response codes on the basis of established stimulus-response (S-R) links. In paradigms of masked S-R priming alerting signals also modulate response activation processes triggered by subliminally presented prime stimuli. In the present study we tested whether facilitation of visuo-motor translation processes due to alerting signals critically depends on established S-R links. Alerting signals resulted in significantly enhanced masked priming effects for masked prime stimuli that included and that did not include established S-R links fi.e., target vs. novel primes). Yet, the alerting-priming interaction was more pronounced for target than for novel primes. These results suggest that effects of alerting signals on masked priming are especially evident when S-R links between prime and target exist. At the same time, an alerting-priming interaction also for novel primes suggests that alerting signals also facilitate stimulus-response translation processes when masked prime stimuli provide action-trigger conditions in terms of programmed S-R links.
Anticipating where an event will occur enables us to instantaneously respond to events that occur at the expected location. Here we investigated if such spatial anticipations can be triggered by symbolic information that participants cannot consciously see. In two experiments involving a Posner cueing task and a visual search task, a central cue informed participants about the likely location of the next target stimulus. In half of the trials, this cue was rendered invisible by pattern masking. In both experiments, visible cues led to cueing effects, that is, faster responses after valid compared to invalid cues. Importantly, even masked cues caused cueing effects, though to a lesser extent. Additionally, we analyzed effects on attention that persist from one trial to the subsequent trial. We found that spatial anticipations are able to interfere with newly formed spatial anticipations and influence orienting of attention in the subsequent trial. When the preceding cue was visible, the corresponding spatial anticipation persisted to an extent that prevented a noticeable effect of masked cues. The effects of visible cues were likewise modulated by previous spatial anticipations, but were strong enough to also exert an impact on attention themselves. Altogether, the results suggest that spatial anticipations can be formed on the basis of unconscious stimuli, but that interfering influences like still active spatial anticipations can suppress this effect.
We used a new methodological approach to investigate whether top-down influences like expertise determine the extent of unconscious processing. This approach does not rely on preexisting differences between experts and novices, but instructs essentially the same task in a way that either addresses a domain of expertise or not. Participants either were instructed to perform a lexical decision task (expert task) or to respond to a combination of single features of word and non-word stimuli (novel task). The stimuli and importantly also the mapping of responses to those stimuli, however, were exactly the same in both groups. We analyzed congruency effects of masked primes depending on the instructed task. Participants performing the expert task responded faster and less error prone when the prime was response congruent rather than incongruent. This effect was significantly reduced in the novel task, and even reversed when excluding identical prime-target pairs. This indicates that the primes in the novel task had an effect on a perceptual level, but were not able to impact on response activation. Overall, these results demonstrate an expertise-based top-down modulation of unconscious processing that cannot be explained by confounds that are otherwise inherent in comparisons between novices and experts.
Recent research revealed that action video game players outperform non-players in a wide range of attentional, perceptual and cognitive tasks. Here we tested if expertise in action video games is related to differences regarding the potential of shortly presented stimuli to bias behavior. In a response priming paradigm, participants classified four animal pictures functioning as targets as being smaller or larger than a reference frame. Before each target, one of the same four animal pictures was presented as a masked prime to influence participants' responses in a congruent or incongruent way. Masked primes induced congruence effects, that is, faster responses for congruent compared to incongruent conditions, indicating processing of hardly visible primes. Results also suggested that action video game players showed a larger congruence effect than non-players for 20 ms primes, whereas there was no group difference for 60 ms primes. In addition, there was a tendency for action video game players to detect masked primes for some prime durations better than non-players. Thus, action video game expertise may be accompanied by faster and more efficient processing of shortly presented visual stimuli.
When a key press causes a stimulus, the key press is perceived later and the stimulus earlier than key presses and stimuli presented independently. This bias in time perception has been linked to the intention to produce the effect and thus been called intentional binding (IB). In recent studies it has been shown that the IB effect is stronger when participants believed that they caused the effect stimulus compared to when they believed that another person caused the effect (Desantis et al., 2011). In this experiment we ask whether causal beliefs influence the perceived time of an effect when the putative effect occurs temporally close to another stimulus that is also an effect. In our study two participants performed the same task on connected computers with separate screens. Each trial started synchro- nously on both computers. When a participant pressed a key, a red and a yellow stimulus appeared as action effects simultaneously or with a slight delay of up to 50 ms. The partic- ipants’ task was to judge the temporal order of these two effect stimuli. Participants were either told that one participant caused one of the two stimuli while the other participant seated at the other computer caused the other stimulus, or each participant was told that he/she caused both stimuli. The different causal beliefs changed the perceived time of the effects’ appearance relative to each other. When participants believed they each caused one effect, their “own” effect was perceived earlier than the other participant’s effect. When the participants believed each caused both effects, no difference in the perceived temporal order of the red and yellow effect was found. These results confirm that higher order causal beliefs change the perceived time of an action effect even in a setting in which the occurrence of the putative effect can be directly compared to a reference stimulus.
In dieser Arbeit werden handlungsdeterminierende Prozesse beim Aufgabenwechsel untersucht. Die ersten durchgeführten Experimente zeigten, dass es notwendig ist, Wechselkosten in verschiedene Teile zu zerlegen, so dass die Dekomposition von Wechselkosten einen großen Teil des Empirieteils ausmacht. Im ersten Kapitel der Arbeit werden verschiedene Theorien zur Handlungsdetermination vorgestellt. Die Theorien werden danach unterschieden, ob sie eher annehmen, dass Umweltreize das menschliche Handeln determinieren oder aber davon ausgehen, dass Handeln überwiegend durch intentionale Prozesse determiniert wird. Zunächst werden der Behaviorismus und einige Ansätze der kognitiven Psychologie erläutert, die den Einfluss von Reizen auf die Handlungsdetermination in den Vordergrund stellen. Das ideomotorische Prinzip dagegen betont die Determination menschlichen Handelns durch das Anstreben von Zielen. Schließlich werden Hybridmodelle (z.B. ABC-Theorie; Hoffmann, 1993) besprochen, die den gemeinsamen Einfluss von Intentionen und Außenreizen auf menschliches Handeln berücksichtigen. Im zweiten und dritten Kapitel wird die Entwicklung des Aufgabenwechselparadigmas und die vermuteten Prozesse und Faktoren beim Aufgabenwechsel erläutert. Ursprünglich wurde das Aufgabenwechselparadigma verwendet, um die Anpassung an flexible Handlungsanforderungen und die dabei notwendigen exekutiven Steuerungsmechanismen zu untersuchen. Doch in vielen Untersuchungen zu Aufgabenwechseln wurde dieses Ziel aus den Augen verloren und die Untersuchung der Vorgänge beim Wechseln wurde zum Selbstzweck. Intentionen und das Anstreben von Zielen wurden innerhalb des Aufgabenwechselparadigmas bisher nicht thematisiert. Im vierten Kapitel wird deshalb versucht Aufgabenwechsel aus der Perspektive der ABC-Theorie (Hoffmann, 1993) zu betrachten, einer Theorie, die sowohl den Einfluss von Intentionen als auch von Außenreizen auf menschliches Handeln berücksichtigt. Aus der ABC-Theorie wurden folgende Vorhersagen für den Aufgabenwechselkontext abgeleitet: 1. Eine parallele Aktivierung verschiedener Handlungsbereitschaften ist prinzipiell möglich. Wechsel zwischen Aufgaben sind nur nötig, wenn sich die Handlungsbereitschaften der Aufgaben widersprechen. 2. Ein Wechsel der Intention und der entsprechenden Handlungsbereitschaften erfolgt sobald die auszuführende Aufgabe feststeht und kann abgeschlossen werden, bevor der Reiz erscheint. Kosten für den exekutiven Prozess des Intentionswechsels können deshalb nur bei kurzer Vorbereitungszeit erfasst werden. Wechselkosten, die nach langer Vorbereitungszeit für die Aufgabe verbleiben (residuale Wechselkosten) spiegeln nicht den Aufwand exekutiver Prozesse wider. 3. Wechsel zwischen Intentionen verursachen mehr exekutiven Aufwand, wenn die Zielzustände der Handlungsbereitschaften überlappen, da dann erst eine Entkopplung des Zielzustandes mit einem Startzustand notwendig ist, bevor der Zielzustand an einen anderen Startzustand gekoppelt werden kann. In den ersten drei Experimenten konnten die Vorhersagen der ABC-Theorie für den Aufgabenwechselkontext nicht bestätigt werden. Beim Vergleich von Durchgängen, in denen die Aufgabe wechselt, mit Durchgängen, in denen die Aufgabe wiederholt wird, zeigten sich auch bei langer Vorbereitungszeit deutliche Wechselkosten, d.h. höhere Reaktionszeiten in den Wechseltrials. Weiterhin ergab sich kein Unterschied der Wechselkosten für Wechsel zwischen Aufgaben mit verschiedenen oder gleichen Zielzuständen (operationalisiert als verschiedene vs. gleiche auszuführende Aktionen). Aus diesen Ergebnissen und vielen Hinweisen in der Aufgabenwechselliteratur ergaben sich Zweifel an der Aussagekraft des herkömmlich berechneten Wechselkostenmaßes als Differenz der Reaktionszeiten bei Aufgabenwechseln minus Aufgabenwiederholungen. Deshalb wird die Entwicklung einer neue Methode zur Dekomposition von Wechselkosten vorgeschlagen, die es ermöglicht, die Reaktionszeitdifferenz zwischen Aufgabenwechseln und Aufgabenwiederholungen in Anteile zu unterteilen, die a) spezifisch die Anforderung beim Wechseln (Intentionswechselkosten) widerspiegeln oder b) durch die Erleichterung eine Reaktion auf denselben Reiz hin zu wiederholen (Repetition Priming) entstehen, oder c) durch die Erschwernis entstehen, auf einen Reiz reagieren zu müssen, auf den zuvor nicht reagiert werden durfte (Negatives Priming). In den Experimenten 4 bis 7 wird diese Methode experimentell validiert. Werden Wechselkosten in die verschiedenen Anteile zerlegt, stimmen die empirischen Befunde mit den Vorhersagen der ABC-Theorie überein: Ein Wechsel der Intention und der entsprechenden Handlungsbereitschaften kann bei genügend langer Vorbereitungszeit abgeschlossen werden, bevor der Stimulus erscheint. Residuale Wechselkosten (Wechselkosten, die bei langer Vorbereitungszeit verbleiben) sind nicht auf exekutive Kontrollprozesse zurückzuführen, sondern durch Repetition Priming und Negatives Priming verursacht. Weiterhin sind Wechsel einfacher, wenn die zu antizipierenden Zielzustände (operationalisiert als die auszuführenden Aktionen) der Aufgaben verschieden sind. In der Abschlussdiskussion werden der theoretische und der methodische Schwerpunkt der Arbeit noch einmal überblicksartig zusammengestellt und es wird ein Ausblick gegeben, wie untersucht werden könnte, ob die ABC-Theorie besser geeignet ist zur Erklärung der Phänomene beim Aufgabenwechsel als bisherige Theorien und Modelle.
One’s own name constitutes a unique part of conscious awareness – but does this also hold true for unconscious processing? The present study shows that the own name has the power to bias a person’s actions unconsciously even in conditions that render any other name ineffective. Participants judged whether a letter string on the screen was a name or a non-word while this target stimulus was preceded by a masked prime stimulus. Crucially, the participant’s own name was among these prime stimuli and facilitated reactions to following name targets whereas the name of another, yoked participant did not. Signal detection results confirmed that participants were not aware of any of the prime stimuli, including their own name. These results extend traditional findings on ‘‘breakthrough’’ phenomena of personally relevant stimuli to the domain of unconscious processing. Thus, the brain seems to possess adroit mechanisms to identify and process such stimuli even in the absence of conscious awareness.