Top-down Set Research Articles

Novel evidence for cue-based retrieval of top-down sets in spatial cueing

Task cues that correctly (vs.incorrectly) inform humans about their upcoming tasks, benefit (vs. interfere with) performance because participants can use task cues to retrieve the corresponding task set, so that targets can (vs. cannot) be processed according to the currently applying task set from target onset onwards. Here, we tested if task-associated features of peripheral cues have a similar effect. Typically, peripheral cues with a task-associated, searched-for color (i.e., top-down matching cues) capture attention: Search for targets presented at the cued position (valid condition) is faster than for targets presented away from the cue (invalid condition), even if cues do not predict the likely target location. For example, when searching for red and green targets, a red cue captures attention even if presented prior to a green target, but a blue cue does not. We know that cue-target color congruence—whether the cue has a target-similar color (congruent case) vs. a target-dissimilar color (incongruent case)—additionally expedites vs. delays search times. However, it is unclear if this congruence effect reflects feed-forward color priming of the target only; or if cue-elicited retrieval of color-specific task sets is involved. Crucially, we hypothesized that cue-based task-set retrieval should incur additional costs if the task sets for the two target colors differ more. In contrast, mere feed-forward priming should not be affected by task-set similarity between color-associated task sets. Congruence effects were indeed larger when color-associated task sets were more different. This finding indicates cue-elicited retrieval of color-associated task sets can contribute to effects of cue-target color congruence. Results are discussed in light of recent theories.

Data-Driven Discovery of Organic Electronic Materials Enabled by Hybrid Top-Down/Bottom-Up Design.

The high-throughput exploration and screening of molecules for organic electronics involves either a 'top-down' curation and mining of existing repositories, or a 'bottom-up' assembly of user-defined fragments based on known synthetic templates. Both are time-consuming approaches requiring significant resources to compute electronic properties accurately. Here, 'top-down' is combined with 'bottom-up' through automatic assembly and statistical models, thus providing a platform for the fragment-based discovery of organic electronic materials. This study generates a top-down set of 117K synthesized molecules containing structures, electronic and topological properties and chemical composition, and uses them as building blocks for bottom-up design. A tool is developed to automate the coupling of these building blocks at their C(sp2/sp)-H bonds, providing a fundamental link between the two dataset construction philosophies. Statistical models are trained on this dataset and a subset of resulting top-down/bottom-up compounds, enabling on-the-fly prediction of ground and excited state properties with high accuracy across organic compound space. With access to ab initio-quality optical properties, this bottom-up pipeline may be applied to any materials design campaign using existing compounds as building blocks. To illustrate this, over a million molecules are screened for singlet fission. tThe leading candidates provide insight into the features promoting this multiexciton-generatingprocess.

Investigating attentional control sets: Evidence for the compilation of multi-feature control sets

Top-down control over stimulus-driven attentional capture, as postulated by the contingent capture hypothesis, has been a topic of lively scientific debate for a number of years now. According to the latter hypothesis, a stimulus has to match the feature of a top-down established control set in order to be selected automatically. Today, research on the topic of contingent capture has focused mostly on the manipulation of only a single feature separating the target from the distractors (the selection feature). The research presented here examined the compilation of top-down attentional control sets having multiple selection features. We report three experiments in which the feature overlap between the distractor and the top-down sets was manipulated on different perceptual features (e.g., colour, orientation and location). Distractors could match three, two or one of the features of the top-down sets. In line with our hypotheses, the strength of the distractor interference effects decreased linearly as the feature overlap between the distractor and the participants’ top-down sets decreased. These results therefore suggest a decline in the efficiency with which distractors involuntarily capture attention as the target-similarity decreases. The data support the idea of multi-feature attentional control sets and are discussed in light of prominent contemporary theories of visual attention.

Harmonising public sector accounting laws and regulations of the European Union member states: powers and competences

This paper analyses the powers and competences of the EU to standardise public sector accounting of the member states and to take other EU action in the field of public sector accounting. We argue that public sector accounting forms part of the administrative organisation of the member states that is not a core EU competence. EU initiatives such as the European Public Sector Accounting Standards project, which aim to increase transparency and comparability, therefore need to follow the rules set out for administrative matters in general. The study reveals on the one hand that EU actions are essentially limited to voluntary cooperation and influences of other policy areas. But on the other hand, it shows that they do not need to be limited to the initiatives currently driven by Eurostat. Points for practitioners The future of the European Public Sector Accounting Standards project is uncertain. However, it is very unlikely that it will take the shape of a top-down set of readymade EU accounting standards that will force public administrations to adjust their inner workings. Public sector accounting is not (yet) a (typical) European policy, but simply a national one that the EU can support. The EU initiative can be considered as an opportunity for collaboration and knowledge sharing on how to increase transparency of public sector accounting.

The influence of reward and top-down task set on goal-directed movements

The influence of reward and top-down task set on goal-directed movements

Searching for emotion: A top-down set governs attentional orienting to facial expressions

Research indicates that humans orient attention toward facial expressions of emotion. Orienting to facial expressions has typically been conceptualised as due to bottom-up attentional capture. However, this overlooks the contributions of top-down attention and selection history. In the present study, across four experiments, these three attentional processes were differentiated using a variation of the dot-probe task, in which participants were cued to attend to a happy or angry face on each trial. Results show that attention toward facial expressions was not exclusively driven by bottom-up attentional capture; instead, participants could shift their attention toward both happy and angry faces in a top-down manner. This effect was not found when the faces were inverted, indicating that top-down attention relies on holistic processing of the face. In addition, no evidence of selection history was found (i.e., no improvement on repeated trials or blocks of trials in which the task was to orient to the same expression). Altogether, these results suggest that humans can use top-down attentional control to rapidly orient attention to emotional faces.

The attractiveness of salient distractors to reaching movements is task dependent

Previous studies in visual attention and oculomotor research showed that a physically salient distractor does not always capture attention or the eyes. Under certain top-down task sets, a salient distractor can be actively suppressed, avoiding capture. Even though previous studies showed that reaching movements are also influenced by salient distractors, it is unclear if and how a mechanism of active suppression of distractors would affect reaching movements. Active suppression might also explain why some studies find reaching movements to curve towards a distractor, while others find reaching movements to curve away. In this study, we varied the top-down task set in two separate experiments by manipulating the certainty about the target location. Participants had to reach for a diamond present among three circles. In Experiments 1 and 3, participants had to search for the reach targets; hence, the target’s location certainty was low. In Experiments 2 and 3, the target’s location was cued before the reach; hence, the target’s location certainty was high. We found that reaches curved towards the physically salient, color singleton, distractor in the search-to-reach task (Experiments 1 and 3), but not in the cued reach task (Experiments 2 and 3). Thus, the saliency of the distractor only attracted reaching movements when the certainty of the target’s location was low. Our findings suggest that the attractiveness of physically salient distractors to reaching movements depends on the top-down task set. The results can be explained by the effect of active attentional suppression on the competition between movement plans.

Attentional priming does not enable observers to ignore salient distractors

ABSTRACTIt is commonly assumed that we find targets faster if we know what they look like. Such top-down guidance plays an important role in theories of visual attention. A recent provocative proposal is that effects attributed to top-down guidance instead reflect attentional priming. Theeuwes and van der Burg [(2011). On the limits of top-down control of visual selection. Attention, Perception, and Psychophysics. 73(7), 2092–2103. doi:10.3758/s13414-011-0176-9] found that observers could not use top-down set to ignore irrelevant singletons but when priming was maximal such distractors could be successfully ignored, suggesting that feature-based top-down selection is impossible but that this can be overcome when a target feature is constant on consecutive trials. Using a variant of their task, we found that participants were unable to ignore a known colour singleton, but also that repetition priming did not help participants ignore the salient distractor. Our results stand in direct contrast to the results of Theeuwes and van der Burg and cast doubt upon the claim that priming effects can explain top-down effects in visual search. Notably the priming effects we do see are mostly episodic rather than featural which means that they cannot serve as a feature-based selection mechanism.

Evaluation of top-down mass spectral identification with homologous protein sequences

BackgroundTop-down mass spectrometry has unique advantages in identifying proteoforms with multiple post-translational modifications and/or unknown alterations. Most software tools in this area search top-down mass spectra against a protein sequence database for proteoform identification. When the species studied in a mass spectrometry experiment lacks its proteome sequence database, a homologous protein sequence database can be used for proteoform identification. The accuracy of homologous protein sequences affects the sensitivity of proteoform identification and the accuracy of mass shift localization.ResultsWe tested TopPIC, a commonly used software tool for top-down mass spectral identification, on a top-down mass spectrometry data set of Escherichia coli K12 MG1655, and evaluated its performance using an Escherichia coli K12 MG1655 proteome database and a homologous protein database. The number of identified spectra with the homologous database was about half of that with the Escherichia coli K12 MG1655 database. We also tested TopPIC on a top-down mass spectrometry data set of human MCF-7 cells and obtained similar results.ConclusionsExperimental results demonstrated that TopPIC is capable of identifying many proteoform spectrum matches and localizing unknown alterations using homologous protein sequences containing no more than 2 mutations.

A graph-based filtering method for top-down mass spectral identification

BackgroundDatabase search has been the main approach for proteoform identification by top-down tandem mass spectrometry. However, when the target proteoform that produced the spectrum contains post-translational modifications (PTMs) and/or mutations, it is quite time consuming to align a query spectrum against all protein sequences without any PTMs and mutations in a large database. Consequently, it is essential to develop efficient and sensitive filtering algorithms for speeding up database search.ResultsIn this paper, we propose a spectrum graph matching (SGM) based protein sequence filtering method for top-down mass spectral identification. It uses the subspectra of a query spectrum to generate spectrum graphs and searches them against a protein database to report the best candidates. As the sequence tag and gaped tag approaches need the preprocessing step to extract and select tags, the SGM filtering method circumvents this preprocessing step, thus simplifying data processing. We evaluated the filtration efficiency of the SGM filtering method with various parameter settings on an Escherichia coli top-down mass spectrometry data set and compared the performances of the SGM filtering method and two tag-based filtering methods on a data set of MCF-7 cells.ConclusionsExperimental results on the data sets show that the SGM filtering method achieves high sensitivity in protein sequence filtration. When coupled with a spectral alignment algorithm, the SGM filtering method significantly increases the number of identified proteoform spectrum-matches compared with the tag-based methods in top-down mass spectrometry data analysis.

A graph-based approach for proteoform identification and quantification using top-down homogeneous multiplexed tandem mass spectra

BackgroundTop-down homogeneous multiplexed tandem mass (HomMTM) spectra are generated from modified proteoforms of the same protein with different post-translational modification patterns. They are frequently observed in the analysis of ultramodified proteins, some proteoforms of which have similar molecular weights and cannot be well separated by liquid chromatography in mass spectrometry analysis.ResultsWe formulate the top-down HomMTM spectral identification problem as the minimum error k-splittable flow problem on graphs and propose a graph-based algorithm for the identification and quantification of proteoforms using top-down HomMTM spectra.ConclusionsExperiments on a top-down mass spectrometry data set of the histone H4 protein showed that the proposed method identified many proteoform pairs that better explain the query spectra than single proteoforms.

A category-specific top-down attentional set can affect the neural responses outside the current focus of attention.

A top-down set can guide attention to enhance the processing of task-relevant objects. Many studies have found that the top-down set can be tuned to a category level. However, it is unclear whether the category-specific top-down set involving a central search task can exist outside the current area of attentional focus. To directly probe the neural responses inside and outside the current focus of attention, we recorded continuous EEG to measure the contralateral ERP components for central targets and the steady-state visual evoked potential (SSVEP) oscillations associated with a flickering checkerboard placed on the visual periphery. The relationship of color categories between targets and non-targets was manipulated to investigate the effect of category-specific top-down set. Results showed that when the color categories of targets and non-targets in the central search arrays were the same, larger SSVEP oscillations were evoked by target color peripheral checkerboards relative to the non-target color ones outside the current attentional focus. However, when the color categories of targets and non-targets were different, the peripheral checkerboards in two different colors of the same category evoked similar SSVEP oscillations, indicating the effects of category-specific top-down set. These results firstly demonstrate that the category-specific top-down set can affect the neural responses of peripheral distractors. The results could support the idea of a global selection account and challenge the attentional window account in selective attention.

Proportional Context of Distracters alters Top-Down Sets during Contingent Attention Capture

Proportional Context of Distracters alters Top-Down Sets during Contingent Attention Capture

Active suppression of salient-but-irrelevant stimuli does not underlie resistance to visual interference

In visual search for a shape target, interference from salient-but-irrelevant color singletons can be resisted in feature search mode, but not in singleton detection mode. In singleton detection mode, we observed a contralateral positivity (PD) after 260–340ms, suggesting that the salient distractor was suppressed. Because RTs in singleton detection mode increased when a distractor was present, we conclude that active suppression of distractors takes time. In feature search mode, no increase in RTs and no PD to the distractor was observed, showing that resistance to interference was not accomplished by suppression. Rather, the smaller N2pc to the target in feature search than in singleton detection mode suggests that enhancement of target features avoided interference. Thus, the strong top-down set in feature search mode eliminated the need to suppress the early attend-to-me signal (corresponding to the Ppc, from 160 to 210ms) that was generated by salient stimuli independently of search mode.

Looking for color while searching for onsets: The efficiency of top-down search sets is influenced by task context

Looking for color while searching for onsets: The efficiency of top-down search sets is influenced by task context

Endogenous attention modulates early selective attention in psychopathy: An ERP investigation.

Psychopathic individuals are prone to act on urges without adequate consideration of future consequences or the rights of other individuals. One interpretation of this behavior is that it reflects abnormal selective attention (i.e., a failure to process information that is incongruent with their primary focus of attention; Hiatt, Schmitt, & Newman, Neuropsychology, 18, 50-59, 2004). Unfortunately, it is unclear whether this selective attention abnormality reflects top-down endogenous influences, such as the strength or specificity of attention focus (i.e., top-down set) apart from other, more exogenous (bottom-up), effects on attention. To explore this question, we used an early visual event-related potential (N2pc) in combination with a modified visual search task designed to assess the effect of early endogenous (i.e., top-down) attention on the processing of set-congruent information. The task was administered to a sample of 70 incarcerated adult males, who were assigned to high, intermediate, and low psychopathy groups using Hare's Psychopathy Checklist-Revised (Hare, 2003). Based on the assumption that their failure to process set-incongruent information reflects the exaggerated effects of endogenous attention, we predicted that participants with high psychopathy scores would show an exaggerated N2pc response to set-congruent information. The results supported the hypothesis and provide novel electrophysiological evidence that psychopathy is associated with exaggerated endogenous attention effects during early stages of processing. Further research is needed to examine the implications of this finding for the well-established failure of psychopathic individuals to process set-incongruent information and inhibit inappropriate responses.

Reward can modulate attentional capture, independent of top-down set.

The traditional distinction between exogenous and endogenous attentional control has recently been enriched with an additional mode of control, termed “selection history.” Recent findings have indicated, for instance, that previously rewarded or punished stimuli capture more attention than their physical attributes would predict. As such, the value that is associated with certain stimuli modulates attentional capture. This particular influence has also been shown for endogenous attention. Although recent leads have emerged, elucidating the influences of reward on exogenous and endogenous attention, it remains unclear to what extent exogenous attention is modulated by reward when endogenous attention is already deployed. We used a Posner cueing task in which exogenous and endogenous cues were presented to guide attention. Crucially, the exogenous cue also indicated the reward value. That is, the color of the exogenous cue indicated how much reward could be obtained on a given trial. The results showed main effects of endogenous and exogenous attention (i.e., speeded reaction times when either cue was valid, as compared to when it was invalid). Crucially, an interaction between exogenous cue validity and reward level was observed, indicating that reward-based associative-learning processes rapidly influence attentional capture, even when endogenous attention has been actively deployed.

Multisensory top-down sets: Evidence for contingent crossmodal capture.

Numerous studies that have investigated visual selective attention have demonstrated that a salient but task-irrelevant stimulus can involuntarily capture a participant's attention. Over the years, a lively debate has erupted concerning the impact of contingent top-down control settings on such stimulus-driven attentional capture. In the research reported here, we investigated whether top-down sets would also affect participants' performance in a multisensory task setting. A nonspatial compatibility task was used, in which the target and the distractor were always presented sequentially from the same spatial location. We manipulated target-distractor similarity by varying the visual and tactile features of the stimuli. Participants always responded to the visual target features (color); the tactile features were incorporated into the participants' top-down set only when the experimental context allowed for the tactile feature to be used in order to discriminate the target from the distractor. Larger compatibility effects after bimodal distractors were observed only when the participants were searching for a bimodal target and when tactile information was useful. Taken together, these results provide the first demonstration of nonspatial contingent crossmodal capture.

Unexpected abrupt onsets can override a top-down set for color.

A substantial literature supports the contention that the involuntary allocation of spatial attention to salient stimuli is contingent on the top-down goals of the observer. However, recent studies suggest that stimuli that violate expectations built up through experience can override top-down set, resulting in cognitively impenetrable, involuntary shifts of spatial attention. The present studies provide a strong test of this hypothesis by manipulating the frequency of presentation of salient, irrelevant, stimuli in spatial cuing and rapid serial visual presentation (RSVP) paradigms. Experiments 1, 2, and 3 found that for targets defined by color, infrequent, uninformative onset precues produce evidence of capture, but that for targets defined by onset, infrequent color singleton precues do not. Experiment 4 provides strong converging evidence for the ability of infrequent onsets to override a top-down set for color; when monitoring an RSVP stream for a colored target, an infrequent onset in the periphery produced a decrement in target report indicative of attentional capture. Together, the results suggest that infrequent onsets represent a special class of stimuli that can produce involuntary shifts of spatial attention that are cognitively impenetrable.

Stimulus-driven attentional capture by subliminal onset cues

In two experiments, we tested whether subliminal abrupt onset cues capture attention in a stimulus-driven way. An onset cue was presented 16 ms prior to the stimulus display that consisted of clearly visible color targets. The onset cue was presented either at the same side as the target (the valid cue condition) or on the opposite side of the target (the invalid cue condition). Because the onset cue was presented 16 ms before other placeholders were presented, the cue was subliminal to the participant. To ensure that this subliminal cue captured attention in a stimulus-driven way, the cue's features did not match the top-down attentional control settings of the participants: (1) The color of the cue was always different than the color of the non-singleton targets ensuring that a top-down set for a specific color or for a singleton would not match the cue, and (2) colored targets and distractors had the same objective luminance (measured by the colorimeter) and subjective lightness (measured by flicker photometry), preventing a match between the top-down set for target and cue contrast. Even though a match between the cues and top-down settings was prevented, in both experiments, the cues captured attention, with faster response times in valid than invalid cue conditions (Experiments 1 and 2) and faster response times in valid than the neutral conditions (Experiment 2). The results support the conclusion that subliminal cues capture attention in a stimulus-driven way.