Visual Attention: Bottom-Up Versus Top-Down

AbstractVisual attention is attracted by salient stimuli that ‘pop out’ from their surroundings. Attention can also be voluntarily directed to objects of current importance to the observer. What happens in the brain when these two processes interact

A Critique of the Attentional Window Account of Capture Failures.

There has been a lengthy debate about whether salient stimuli have the power to automatically capture attention, even when entirely task irrelevant. Theeuwes (2022) has suggested that an attentional window account could explain why capture is observed in some studies, but not others. According to this account, when search is difficult, participants narrow their attentional window, and this prevents the salient distractor from generating a saliency signal. In turn, this causes the salient distractor to fail to capture attention. In the present commentary, we describe two major problems with this account. First, the attentional window account proposes that attention must be focused so narrowly that featural information from the salient distractor will be filtered prior to saliency computations. However, many previous studies observing no capture provided evidence that featural processing was sufficiently detailed to guide attention toward the target shape. This indicates that the attentional window was sufficiently broad to allow featural processing. Second, the attentional window account proposes that capture should occur more readily in easy search tasks than difficult search tasks. We review previous studies that violate this basic prediction of the attentional window account. A more parsimonious account of the data is that control over feature processing can be exerted proactively to prevent capture, at least under certain conditions

Detection is unaffected by the deployment of focal attention

There has been much debate regarding how much information humans can extract from their environment without the use of limited attentional resources. In a recent study, Theeuwes, Van der Burg, and Belopolsky (2008) argued that even detection of simple feature targets is not possible without selection by focal attention. Supporting this claim, they found response time benefits in a simple feature (color) detection task when a target letter’s identity was repeated on consecutive trials, suggesting that the letter was selected by focal attention and identified prior to detection. This intertrial repetition benefit remained even when observers were required to simultaneously identify a central digit. However, we found that intertrial repetition benefits disappeared when a simple color target was presented among a heterogeneously (rather than homogeneously) colored set of distractors, thus reducing its bottom-up salience. Still, detection performance remained high. Thus, detection performance was unaffected by whether a letter was focally attended and identified prior to detection or not. Intertrial identity repetition benefits also disappeared when observers were required to perform a simultaneous, attention-demanding central task (Experiment 2), or when unfamiliar Chinese characters were used (Experiment 3). Together, these results suggest that while shifts of focal attention can be affected by target salience, by the availability of excess cognitive resources, and by target familiarity, detection performance itself is unaffected by these manipulations and is thus unaffected by the deployment of focal attention

Massive memory revisited: Limitations on storage capacity for object details in visual long-term memory

Previous work suggests that visual long-term memory (VLTM) is highly detailed and has a massive capacity. However, memory performance is subject to the effects of the type of testing procedure used. The current study examines detail memory performance by probing the same memories within the same subjects, but using divergent probing methods. The results reveal that while VLTM representations are typically sufficient to support performance when the procedure probes gist-based information, they are not sufficient in circumstances when the procedure requires more detail. We show that VLTM capacity, albeit large, is heavily reliant on gist as well as detail. Thus, the nature of the mnemonic representations stored in VLTM is important in understanding its capacity limitations