Task-irrelevant semantic relationship between objects and scene influence attentional allocation.

Recent behavioral evidence suggests that the semantic relationships between isolated objects can influence attentional allocation, with highly semantically related objects showing an increase in processing efficiency. This semantic influence is present even when it is task-irrelevant (i.e., when semantic information is not central to the task). However, given that objects exist within larger contexts, i.e., scenes, it is critical to understand whether the semantic relationship between a scene and its objects continuously influence attention. Here, we investigated the influence of task-irrelevant scene semantic properties on attentional allocation and the degree to which semantic relationships between scenes and objects interact. Results suggest that task-irrelevant associations between scenes and objects continuously influence attention and that this influence is directly predicted by the perceived strength of semantic associations.

Thematic object pairs produce stronger and faster grouping than taxonomic pairs.

Studies of visual object processing have long appreciated that semantic meaning is automatically extracted. However, "semantics" has largely been defined as a unitary concept that describes all meaning-based information. In contrast, the concept literature divides semantics into taxonomic and thematic types. Taxonomic relationships reflect categorization by similarities (e.g., dog-wolf); thematic groups are based on complementary relationships (e.g., swimsuit-goggles). Critically, thematic relationships are learned from the experienced co-occurrence of objects whereas taxonomic relationships are based on shared structural similarities. In two studies with adults (N = 66 Experiment 1; N = 44 Experiment 2), we test whether visual processing of thematic objects is more rapid because they form a perceptual unit and serve as mutual visual primes. The results demonstrate that visual processing benefits between thematically related objects are earlier than taxonomic ones, revealing a link between how information is acquired (e.g., experienced vs. unobserved) and how it modulates perception. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Task-Irrelevant Semantic Properties of Objects Impinge on Sensory Representations within the Early Visual Cortex.

Objects can be described in terms of low-level (e.g., boundaries) and high-level properties (e.g., object semantics). While recent behavioral findings suggest that the influence of semantic relatedness between objects on attentional allocation can be independent of task-relevance, the underlying neural substrate of semantic influences on attention remains ill-defined. Here, we employ behavioral and functional magnetic resonance imaging measures to uncover the mechanism by which semantic information increases visual processing efficiency. We demonstrate that the strength of the semantic relatedness signal decoded from the left inferior frontal gyrus: 1) influences attention, producing behavioral semantic benefits; 2) biases spatial attention maps in the intraparietal sulcus, subsequently modulating early visual cortex activity; and 3) directly predicts the magnitude of behavioral semantic benefit. Altogether, these results identify a specific mechanism driving task-independent semantic influences on attention.

Target frequency modulates object-based attention.

Decades of research have provided evidence that object representations contribute to attentional selection. However, most evidence for object-based attentional allocation is drawn from studies employing the two-rectangle paradigm where the target distribution is biased towards the cued object. It is thus unclear whether object-based attentional selection is from object representations or a consequence of spatial attention based on statistical imbalances. Here, we investigate the extent to which target frequency modulates object-based attention by systematically manipulating the frequency of target appearance in a particular spatial location within objects to equate spatial allocation, bias specific spatial locations, or bias objects. In four experiments, participants were presented with a variant of the two-rectangle paradigm in which one end of a rectangle was cued and performed a target discrimination task. Critically, the target location probabilities were parametrically manipulated. The target could appear equally in all ends within the objects (valid, invalid within-object, invalid between-object, diagonal) (Experiment 1) or with overall equality between objects but biased towards the invalid locations (Experiment 2). The target could also appear in three locations (valid, invalid within-object, invalid between-object) distributed equally between objects but biased towards the invalid between-object location (Experiment 3) or with an overall bias towards the invalid between-object location (Experiment 4). We observed that while objects bias attention, spatial biases are prioritized over object representations. Combined results suggest that object-based contribution to attentional guidance is the result of both spatial probabilities and object representations.

Neural Correlates of Perceptual Grouping Under Conditions of Inattention and Divided Attention.

Grouping local elements of the visual environment together is crucial for meaningful perception. While our attentional system facilitates perception, it is limited in that we are unaware of some aspects of our environment that can still influence how we experience it. In this study, the neural mechanisms underlying the Ponzo illusion were examined under inattention and divided-attention conditions using functional magnetic resonance imaging to investigate the brain regions responsible for accessing visual stimuli. A line discrimination task was performed in which two horizontal lines were superimposed on a background of black and white dots that, on occasion, induced the Ponzo illusion if perceptually grouped together. Our findings revealed activation for perceptual grouping in the frontal, parietal, and occipital regions of the brain and activation in the bilateral frontal, temporal, and cingulate gyrus in response to divided attention compared with inattention trials. A direct comparison between grouping and attention showed involvement of the right supramarginal gyrus in grouping specifically under conditions of inattention, suggesting that even during implicit grouping complex visual processing occurs. Given that much of the visual world is not represented in conscious perception, these findings provide crucial information about how we make sense of visual scenes in the world.

Invalidly cued targets are well localized when detected.

Considerable attention has been devoted to understanding how objects are localized when there is ample time and attention to detect them. However, in the real world, we often must react to, or act upon, objects that we have glimpsed only briefly and are not directly at the focus of our attention. This paper describes two experiments examining the role of attentional constraints on 2-D (directional) localization, particularly in cases in which targets have been detected but are not within the spatial focus of attention. Targets were asterisks presented briefly (34-150 ms) above or below a central fixation point. Just prior to the target's appearance, a cue directed attention toward, or away from, the target. Participants indicated whether or not they saw the target, and then used a mouse to indicate the target's location. The impact of guessing was mitigated by removing trials that participants had flagged as not detected. Longer glimpses generally benefitted localization; by contrast, cue validity had very little effect on response sensitivity, bias or precision. At very brief durations, invalid cueing did result in a small increase in foveal bias. These results indicate that the directional location of objects can be extracted reasonably well from brief glimpses even with reduced attention. This directional information provides an important basis for 3-D localization of objects on the ground, via their angular declination. The current studies suggest that egocentric distance perception might be similarly robust to reduced attention when localization is based primarily on a target's angular declination.

Attention scales according to inferred real-world object size.

Natural scenes consist of objects of varying shapes and sizes. The impact of object size on visual perception has been well-demonstrated, from classic mental imagery experiments1, to recent studies of object representations reporting topographic organization of object size in the occipito-temporal cortex2. While the role of real-world physical size in perception is clear, the effect of inferred size on attentional selection is ill-defined. Here, we investigate whether inferred real-world object size influences attentional allocation. Across five experiments, attentional allocation was measured in objects of equal retinal size, but varied in inferred real-world size (for example, domino, bulldozer). Following each experiment, participants rated the real-world size of each object. We hypothesized that, if inferred real-world size influences attention, selection in retinal size-matched objects should be less efficient in larger objects. This effect should increase with greater attentional demand. Predictions were supported by faster identified targets in objects inferred to be small than large, with costlier attentional shifting in large than small objects when attentional demand was high. Critically, there was a direct correlation between the rated size of individual objects and response times (and shifting costs). Finally, systematic degradation of size inference proportionally reduced object size effect. It is concluded that, along with retinal size, inferred real-world object size parametrically modulates attention. These findings have important implications for models of attentional control and invite sensitivity to object size for future studies that use real-world images in psychological research.

Intrusive effects of task-irrelevant information on visual selective attention: semantics and size.

Attentional selection is a mechanism by which incoming sensory information is prioritized for further, detailed, and more effective, processing. Given that attended information is privileged by the sensory system, understanding and predicting what information is granted prioritization becomes an important endeavor. It has been argued that salient events as well as information that is related to the current goal of the organism (i.e., task-relevant) receive such a priority. Here, we propose that attentional prioritization is not limited to task-relevance, and discuss evidence showing that task-irrelevant, non-salient, high-level properties of unattended objects, namely object meaning and size, influence attentional allocation. Such an intrusion of non-salient, task-irrelevant, high-level information points to the need to re-conceptualize and formally modify current models of attentional guidance.

Mammography to tomosynthesis: examining the differences between two-dimensional and segmented-three-dimensional visual search.

BACKGROUND: Radiological techniques for breast cancer detection are undergoing a massive technological shift-moving from mammography, a process that takes a two-dimensional (2D) image of breast tissue, to tomosynthesis, a technique that creates a segmented-three-dimensional (3D) image. There are distinct benefits of tomosynthesis over mammography with radiologists having fewer false positives and more accurate detections; yet there is a significant and meaningful disadvantage with tomosynthesis in that it takes longer to evaluate each patient. This added time can dramatically impact workflow and have negative attentional and cognitive impacts on interpretation of medical images. To better understand the nature of segmented-3D visual search and the implications for radiology, the current study looked to establish a new testing platform that could reliably examine differences between 2D and segmented-3D search. RESULTS: In Experiment 1, both professionals (radiology residents and certified radiologists) and non-professionals (undergraduate students) were found to have fewer false positives and were more accurate in segmented-3D displays, but at the cost of taking significantly longer in search. Experiment 2 tested a second group of non-professional participants, using a background that more closely resembled a mammogram, and replicated the results of Experiment 1-search was more accurate and there were fewer false alarms in segmented 3D displays but took more time. CONCLUSION: The results of Experiments 1 and 2 matched the performance patterns found in previous radiology studies and in the clinic, suggesting this novel experimental paradigm potentially provides a flexible and cost-effective tool that can be utilized with non-professional populations to inform relevant visual search performance. From an academic perspective, this paradigm holds promise for examining the nature of segmented-3D visual search.

Object width modulates object-based attentional selection.

Visual input typically includes a myriad of objects, some of which are selected for further processing. While these objects vary in shape and size, most evidence supporting object-based guidance of attention is drawn from paradigms employing two identical objects. Importantly, object size is a readily perceived stimulus dimension, and whether it modulates the distribution of attention remains an open question. Across four experiments, the size of the objects in the display was manipulated in a modified version of the two-rectangle paradigm. In Experiment 1, two identical parallel rectangles of two sizes (thin or thick) were presented. Experiments 2-4 employed identical trapezoids (each having a thin and thick end), inverted in orientation. In the experiments, one end of an object was cued and participants performed either a T/L discrimination or a simple target-detection task. Combined results show that, in addition to the standard object-based attentional advantage, there was a further attentional benefit for processing information contained in the thick versus thin end of objects. Additionally, eye-tracking measures demonstrated increased saccade precision towards thick object ends, suggesting that Fitts's Law may play a role in object-based attentional shifts. Taken together, these results suggest that object-based attentional selection is modulated by object width.