Top-down versus bottom-up attentional control: a failed theoretical dichotomy

Prominent models of attentional control assert a dichotomy between top-down and bottom-up control, with the former determined by current selection goals and the latter determined by physical salience. This theoretical dichotomy, however, fails to explain a growing number of cases in which neither current goals nor physical salience can account for strong selection biases. For example, equally salient stimuli associated with reward can capture attention, even when this contradicts current selection goals. Thus, although 'top-down' sources of bias are sometimes defined as those that are not due to physical salience, this conception conflates distinct--and sometimes contradictory--sources of selection bias. We describe an alternative framework, in which past selection history is integrated with current goals and physical salience to shape an integrated priority map.     

Top-down and bottom-up control of visual selection

The present paper argues for the notion that when attention is spread across the visual field in the first sweep of information through the brain visual selection is completely stimulus-driven. Only later in time, through recurrent feedback processing, volitional control based on expectancy and goal set will bias visual selection in a top-down manner. Here we review behavioral evidence as well as evidence from ERP, fMRI, TMS and single cell recording consistent with stimulus-driven selection. Alternative viewpoints that assume a large role for top-down processing are discussed. It is argued that in most cases evidence supporting top-down control on visual selection in fact demonstrates top-down control on processes occurring later in time, following initial selection. We conclude that top-down knowledge regarding non-spatial features of the objects cannot alter the initial selection priority. Only by adjusting the size of the attentional window, the initial sweep of information through the brain may be altered in a top-down way.     

Top-down and bottom-up sequential modulations of congruency effects

Several studies have demonstrated reduced congruency effects after incongruent trials. The conflict monitoring hypothesis (Botvinick, Braver, Barch, Carter, & Cohen, 2001) assumes that this sequential modulation is based on top-down cognitive control and suggests that more control is engaged after the detection of conflict. An alternative account is based on repetition effects of stimulus and response features and can be considered bottom up. This study investigates both modulatory sources. In a Stroop task with two response-stimulus intervals (RSIs), we demonstrate that top-down modulation does not occur with a very short RSI, suggesting that it takes some time before the system can be reconfigured. Bottom-up modulation is observed for both RSIs. This finding demonstrates that two different sources simultaneously reduce congruency effects after incongruent trials.     

The effects of a salient self-schema on the evaluation of proattitudinal editorials: Top-down versus bottom-up message processing

The effects of a salient self-schema on message evaluation were studied. Subjects were identified who characterized themselves using trait adjectives that reflected the prototype of either a “religious” or a “legalistic” person. Equally persuasive sets of proattitudinal messages were developed empirically using weak arguments. Half of the messages were developed to reflect a “religious” perspective on the issue (capital punishment, abortion) whereas half were developed to reflect a “legalistic” perspective on the issue. Religious and legalistic subjects were then exposed to religious or legalistic arguments supporting an equally acceptable position (e.g., eliminating capital punishment). Afterward, subjects evaluated the persuasiveness of the communication and listed their thoughts as part of a “curriculum development project.” Results suggested that subjects when exposed to a schema-relevant message arguments for a position in which they believed were more positive about the quality of the message arguments and in their cognitive responding. These data extend the heuristic value of selfschemata to the area of attitudes and suggest that cognitive responses in persuasion are subjectively rather than objectively rational.     

Visual search in children and adults: Top-down and bottom-up mechanisms

Three experiments investigated visual search for targets that differed from distractors in colour, size, or orientation. In one condition the target was defined by a conjunction of these features, while in the other condition the target was the odd one out. In all experiments, 6–7- and 9–10-year-old children were compared with young adults. Experiment 1 showed that children's search differed from adults' search in two ways. In conjunction searches children searched more slowly and took longer to reject trials when no target was present. In the odd-one-out experiments, 6–7-year-old children were slower to respond to size targets than to orientation targets, and slower for orientation targets than for colour targets. Both the other groups showed no difference in their rate of responding to colour and orientation. Experiments 2 and 3 highlighted that these results were not a function of either differential density across set sizes (Experiment 2) or discriminability of orientation and colour (Experiment 3). Across all three experiments, the results of both conjunction and odd-one-out searches highlighted a development in visual search from middle to late childhood.     

Working memory capacity and visual attention: Top-down and bottom-up guidance

Previous studies have indicated that working memory capacity (WMC) is related to visual attention when selection of critical information must be made in the face of distraction. The present study examines whether WMC-related differences in flanker task performance might be decreased by displays that are designed to support bottom-up guidance of attention. Participants were required to respond to a centrally located target while ignoring a peripheral flanker. In one condition, bottom-up support was provided by embedding the target in a row of zeros. In another condition, the zeros were removed, thus emphasizing the role of top-down attention in selecting spatially defined information. It was found that the inclusion of zeros led to the elimination of WMC-related flanker effects. We conclude that bottom-up attentional guidance can attenuate the role of WMC in selective attention.     

Multistable perception: when bottom-up and top-down coincide

During prolonged observation of an ambiguous figure sudden perceptual reversals occur, while the stimulus itself stays unchanged. There is a vivid debate about whether bottom-up or top-down mechanisms underlie this phenomenon. In the present study, we investigated the interrelation of two experimental factors: volitional control and discontinuous stimulus presentation. Both factors strongly modulate the rate of perceptual reversals and each is attributed either as top-down or bottom-up. We found that participants can apply specific strategies to volitionally increase and/or decrease the stability duration of each of the possible percepts according to the experimental instructions. When attempts of volitional control are combined with discontinuous stimulus presentation the effects are fully additive. Our results indicate that perceptual reversals can originate from different neural mechanisms on different time scales.     

Measuring automatic retrieval

A variety of procedures have been used to assess automatic retrieval effects on memory, including implicit memory tests and the process dissociation approach. Theoretical concerns with each are summarized prior to describing a procedure for evaluating automatic retrieval that is based on retrieval speed. Specifically, in a speeded implicit task, participants were encouraged to complete word stems using strictly automatic retrieval by presenting several practice test trials that did not allow responding based on previously studied items and by encouraging speed of responding. This speeded implicit task was compared with a condition in which conscious retrieval of studied information was not possible and a condition in which conscious retrieval was required, providing converging evidence to support the hypothesis that the speeded implicit procedure can yield pure estimates of automatic retrieval. Furthermore, evidence from a standard implicit memory task yielded comparable data that suggests that participants engaged automatic retrieval processes on this task also.     

Top-down and bottom-up attentional control: On the nature of interference from a salient distractor

In two experiments using spatial probes, we measured the temporal and spatial interactions between top-down control of attention and bottom-up interference from a salient distractor in visual search. The subjects searched for a square among circles, ignoring color. Probe response times showed that a color singleton distractor could draw attention to its location in the early stage of visual processing (before a 100-msec stimulus onset asynchrony [SOA]), but only when the color singleton distractor was located far from the target. Apparently the bottom-up activation of the singleton distractor’s location is affected early on by local interactions with nearby stimulus locations. Moreover, probe results showed that a singleton distractor did not receive attention after extended practice. These results suggest that top-down control of attention is possible at an early stage of visual processing. In the long-SOA condition (150-msec SOA), spatial attention selected the target location over distractor locations, and this tendency occurred with or without extended practice.     

Implicit proactive interference, age, and automatic versus controlled retrieval strategies

We assessed the extent to which implicit proactive interference results from automatic versus controlled retrieval among younger and older adults. During a study phase, targets (e.g., "ALLERGY") either were or were not preceded by nontarget competitors (e.g., "ANALOGY"). After a filled interval, the participants were asked to complete word fragments, some of which cued studied words (e.g., "A_L_ _GY"). Retrieval strategies were identified by the difference in response speed between a phase containing fragments that cued only new words and a phase that included a mix of fragments cuing old and new words. Previous results were replicated: Proactive interference was found in implicit memory, and the negative effects were greater for older than for younger adults. Novel findings demonstrate two retrieval processes that contribute to interference: an automatic one that is age invariant and a controlled process that can reduce the magnitude of the automatic interference effects. The controlled process, however, is used effectively only by younger adults. This pattern of findings potentially explains age differences in susceptibility to proactive interference.     

Top-down and bottom-up attentional control: on the nature of interference from a salient distractor.

In two experiments using spatial probes, we measured the temporal and spatial interactions between top-down control of attention and bottom-up interference from a salient distractor in visual search. The subjects searched for a square among circles, ignoring color. Probe response times showed that a color singleton distractor could draw attention to its location in the early stage of visual processing (before a 100-msec stimulus onset asynchrony [SOA]), but only when the color singleton distractor was located far from the target. Apparently the bottom-up activation of the singleton distractor's location is affected early on by local interactions with nearby stimulus locations. Moreover, probe results showed that a singleton distractor did not receive attention after extended practice. These results suggest that top-down control of attention is possible at an early stage of visual processing. In the long-SOA condition (150-msec SOA), spatial attention selected the target location over distractor locations, and this tendency occurred with or without extended practice.     

Prioritizing selection of new elements: bottom-up versus top-down control

Watson and Humphreys (1997) have proposed that prioritized selection of new over old elements occurs because observers can apply top-down inhibition to the locations of the old elements by a mechanism they refer to as visual marking. However, recent evidence has suggested that the top-down mechanism is questionable (Donk & Theeuwes, 2001). In the present study, we investigated whether prioritized selection of new over old elements occurs in a bottom-up or a top-down fashion. Observers were presented with displays containing one set of elements (old elements) followed, after a certain time interval, by a second set of elements (new elements). The observers were instructed to search for the presence of a target that was presented with equal probability among the old and the new elements (Experiments 1 and 2) or twice as often among the old elements than among the new elements (Experiment 3). The results show that new elements were prioritized for selection over old ones even though the observers had no incentive to do so. The results suggest that prioritized selection of new over old elements is not mediated by a top-down inhibition process, as was proposed by Watson and Humphreys (1997). Instead, prioritization of new elements appears to be a bottom-up process. The implications of these results are discussed in terms of models of attentional control.     

Duemmler, Kerstin; Nagel, Alexander-Kenneth: Governing Religious Diversity: Top-down and bottom-up initiatives in Germany and Switzerland

In recent years religious pluralization has become a significant policy issue in Western societies as a result of a new awareness of religion and of religious minorities articulating themselves and becoming more visible. The article explores the variety of social and political reactions to religious diversity in urban areas and in doing so it brings together theoretical concepts of political and cultural sociology. The notion of diversity governance as joint endeavour of state and societal actors managing societies is linked to the notion of boundary work as interplay of state and/or societal actors maintaining or modifying boundaries between religious traditions. Based on two case studies the article illustrates two idealtypical settings of diversity governance: The first case from the German Ruhr Area stands for a bottom-up approach which is based on civic self-organization of interreligious activities whereas the second case from the Swiss canton of Lucerne exhibits a model of top-down governance based on state interventions in religious instruction at schools. Drawing on semi-structured interviews and participant observation the authors show how different governance settings shape the construction and blurring of boundaries in the religious field. Both approaches operate differently when incorporating religious diversity and rendering former homogenous notions of we-groups more heterogeneous. Despite of the approaches initial aim of inclusion, patterns of exclusion are equally reproduced since the idea of ‘legitimate religion’ rooted in Christian majority culture is present.     

Multiple processes in prospective memory retrieval: factors determining monitoring versus spontaneous retrieval

Theoretically, prospective memory retrieval can be accomplished either by controlled monitoring of the environment for a target event or by a more reflexive process that spontaneously responds to the presence of a target event. These views were evaluated in Experiments 1-4 by examining whether performing a prospective memory task produced costs on the speed of performing the ongoing task. In Experiment 5, the authors directly tested for the existence of spontaneous retrieval. The results supported the multiprocess theory (M. A. McDaniel & G. O. Einstein, 2000) predictions that (a) spontaneous retrieval can occur and can support good prospective memory and (b) depending on task demands and individual differences, people rely to different degrees on monitoring versus spontaneous retrieval for prospective remembering.     

Binary choice under instructions to select versus reject

Two experiments examine differences in binary choice under select versus reject instructions. Three aspects of the choice process are examined: commitment to the chosen alternative, absolute magnitude of attribute evaluations, and information distortion during the choice process. Although the findings support previously hypothesized causes (Study 1), these results are reversed when the decision alternatives are uniformly negative (Study 2a). Accompanying verbal protocols (Study 2b) provide additional insights into the underlying decision process. The results consistently support a compatibility effect. Whenever there is a match between the valences of the alternatives and of the decision strategy, namely selecting a positive alternative or rejecting a negative one, there is greater accentuation of attribute differences, higher certainty in the final choice, and more information distortion. Metaphorically, the choice process seems to flow more smoothly in the compatible conditions.