Inattentional blindness: Attentional set for efficient task success.

Inattentional blindness is the failure to notice an unexpected object in plain sight when attention is otherwise engaged. We investigated what determines observers' attentional set in a dynamic-counting inattentional blindness paradigm, when task instructions and visual distinctiveness of task-relevant objects were either congruent or in opposition. In seven experiments, observers counted bounces by task-relevant objects, with the instruction either to count-by-shape (squares, diamonds, crosses) or count-by-colour (blue, purple). To manipulate visual distinctiveness, we varied the extent to which task-relevant and task-irrelevant objects looked different on two dimensions: shape and colour. When colour better distinguished task-relevant from task-irrelevant objects, observers-even if instructed count-by-shape-reported an unexpected object that matched the colour of task-relevant objects. Crucially, when instructed count-by-colour, but shape better distinguished task-relevant from task-irrelevant objects, observers reported an unexpected object that matched the shape of task-relevant objects. We conclude that observers set their attention to promote efficient task performance.

The vocabulary spurt predicts the emergence of backward semantic inhibition in 18-month-old toddlers.

The current study examines the relationship between 18-month-old toddlers' vocabulary size and their ability to inhibit attention to no-longer relevant information using the backward semantic inhibition paradigm. When adults switch attention from one semantic category to another, the former and no-longer-relevant semantic category becomes inhibited, and subsequent attention to an item that belongs to the inhibited semantic category is impaired. Here we demonstrate that 18-month-olds can inhibit attention to no-longer relevant semantic categories, but only if they have a relatively large vocabulary. These findings suggest that an increased number of items (word knowledge) in the toddler lexical-semantic system during the "vocabulary spurt" at 18-months may be an important driving force behind the emergence of a semantic inhibitory mechanism. Possessing more words in the mental lexicon likely results in the formation of inhibitory links between words, which allow toddlers to select and deselect words and concepts more efficiently. Our findings highlight the role of vocabulary growth in the development of inhibitory processes in the emerging lexical-semantic system.

Focal CA3 hippocampal subfield atrophy following LGI1 VGKC-complex antibody limbic encephalitis.

Magnetic resonance imaging has linked chronic voltage-gated potassium channel (VGKC) complex antibody-mediated limbic encephalitis with generalized hippocampal atrophy. However, autoantibodies bind to specific rodent hippocampal subfields. Here, human hippocampal subfield (subiculum, cornu ammonis 1-3, and dentate gyrus) targets of immunomodulation-treated LGI1 VGKC-complex antibody-mediated limbic encephalitis were investigated using in vivo ultra-high resolution (0.39 × 0.39 × 1.0 mm3) 7.0 T magnetic resonance imaging [n = 18 patients, 17 patients (94%) positive for LGI1 antibody and one patient negative for LGI1/CASPR2 but positive for VGKC-complex antibodies, mean age: 64.0 ± 2.55 years, median 4 years post-limbic encephalitis onset; n = 18 controls]. First, hippocampal subfield quantitative morphometry indicated significant volume loss confined to bilateral CA3 [F(1,34) = 16.87, P < 0.0001], despite hyperintense signal evident in 5 of 18 patients on presentation. Second, early and later intervention (<3 versus >3 months from symptom onset) were associated with CA3 atrophy. Third, whole-brain voxel-by-voxel morphometry revealed no significant grey matter loss. Fourth, CA3 subfield atrophy was associated with severe episodic but not semantic amnesia for postmorbid autobiographical events that was predicted by variability in CA3 volume. The results raise important questions about the links with histopathology, the impact of the observed focal atrophy on other CA3-mediated reconstructive and episodic mechanisms, and the role of potential antibody-mediated pathogenicity as part of the pathophysiology cascade in humans.

Inattentional blindness on the full-attention trial: Are we throwing out the baby with the bathwater?

When attention is otherwise engaged, observers may experience inattentional blindness, failing to notice objects or events that are presented in plain sight. In an inattentional blindness experiment, an unexpectedstimulus ispresented alongside primary-task stimuli, and its detection is probed. We evaluate a criterion that is commonly used to exclude observers from the data analysis. On the final experimental trial, observers do not perform the primary task, but instead look for anything new. Observers who fail to report the unexpected stimulus on thisfull-attention trialare excluded. On the basis of 4 hypothetical experiments and a review of 128 actual experiments from the literature, we demonstrate some potentially problematic consequences of implementing the full-attention-trial exclusion criterion. Excluded observers may cluster in experimental conditions and the exclusion criterion may lead researchers to understate the pervasiveness of inattentional blindness. It may even render usblindto inattentional blindness on the full-attention trial.

Backward Semantic Inhibition in Toddlers.

Attention switching is a crucial ability required in everyday life, from toddlerhood to adulthood. In adults, shifting attention from one word (e.g., dog) to another (e.g., sea) results in backward semantic inhibition, that is, the inhibition of the initial word ( dog). In this study, we used the preferential-looking paradigm to examine whether attention switching is accompanied by backward semantic inhibition in toddlers. We found that 24-month-olds can indeed refocus their attention to a new item by selectively inhibiting attention to the old item. The consequence of backward inhibition is that subsequent attention to a word semantically related to the old item is impaired. These findings have important implications for understanding the underlying mechanism of backward semantic inhibition and the development of lexical-semantic inhibition in early childhood.

Does animacy affect visual statistical learning? Revisiting the effects of selective attention and animacy on visual statistical learning.

Animates receive preferential attentional processing over inanimates because, from an evolutionary perspective, animates are important to human survival. We investigated whether animacy affects visual statistical learning-the detection and extraction of regularities in visual information from our rich, dynamic, and complex environment. Participants completed a selective-attention task, in which regularities were embedded in two visual streams, an attended and an unattended visual stream. The attended visual stream always consisted of line-drawings of non-objects, while the unattended visual stream consisted of line-drawings of either animates or inanimates. Participants then completed a triplet-discrimination task, which assessed their ability to extract regularities from the attended and unattended visual streams. We also assessed participants' awareness of regularities in the visual statistical learning task, and asked if any learning strategies were used. We were specifically interested in whether the animacy status of line-drawings in the unattended visual stream would affect visual statistical learning. There were four key findings. First, selective attention modulates visual statistical learning, with greater visual statistical learning for attended than for unattended information. Second, animacy does not affect visual statistical learning, with no differences found in visual statistical learning performance between the animate and inanimate condition. Third, awareness of regularities was associated with visual statistical learning of attended information. Fourth, participants used strategies (e.g., naming or labelling stimuli) during the visual statistical learning task. Further research is required to understand whether visual statistical learning is one of the adaptive functions that evolved from ancestral environments.

Spatial limits on the nonvisual self-touch illusion and the visual rubber hand illusion: subjective experience of the illusion and proprioceptive drift.

The nonvisual self-touch rubber hand paradigm elicits the compelling illusion that one is touching one's own hand even though the two hands are not in contact. In four experiments, we investigated spatial limits of distance (15 cm, 30 cm, 45 cm, 60 cm) and alignment (0°, 90° anti-clockwise) on the nonvisual self-touch illusion and the well-known visual rubber hand illusion. Common procedures (synchronous and asynchronous stimulation administered for 60s with the prosthetic hand at body midline) and common assessment methods were used. Subjective experience of the illusion was assessed by agreement ratings for statements on a questionnaire and time of illusion onset. The nonvisual self-touch illusion was diminished though never abolished by distance and alignment manipulations, whereas the visual rubber hand illusion was more robust against these manipulations. We assessed proprioceptive drift, and implications of a double dissociation between subjective experience of the illusion and proprioceptive drift are discussed.

When you fail to see what you were told to look for: inattentional blindness and task instructions.

Inattentional blindness studies have shown that an unexpected object may go unnoticed if it does not share the property specified in the task instructions. Our aim was to demonstrate that observers develop an attentional set for a property not specified in the task instructions if it allows easier performance of the primary task. Three experiments were conducted using a dynamic selective-looking paradigm. Stimuli comprised four black squares and four white diamonds, so that shape and colour varied together. Task instructions specified shape but observers developed an attentional set for colour, because we made the black-white discrimination easier than the square-diamond discrimination. None of the observers instructed to count bounces by squares reported an unexpected white square, whereas two-thirds of observers instructed to count bounces by diamonds did report the white square. When attentional set departs from task instructions, you may fail to see what you were told to look for.

Age differences in visual statistical learning: Investigating the effects of selective attention and stimulus category.

A cognitive function that is of interest when investigating age-related changes is statistical learning-the ability to detect and extract regularities in sensory information from our rich, dynamic, and complex environment. A previous study has suggested that there were age differences in visual statistical learning, with older adults demonstrating visual statistical learning of attended and unattended information (due to the "hyper-binding effect"). In the present study, we were interested in investigating whether there are age differences in visual statistical learning and whether stimulus category influenced visual statistical learning of unattended information in older adults. We tested two stimulus categories: highly familiar line drawings and abstract shapes. Participants completed a selective-attention task, in which regularities were embedded into both the attended and unattended visual streams. Then, participants completed a triplet-discrimination task, which assessed their ability to extract regularities from the attended and unattended visual streams. We also implemented a 4-point confidence-rating scale in the triplet-discrimination task as an assessment of participants' awareness of these regularities. There were four key findings. First, selective attention modulates visual statistical learning, with greater visual statistical learning for attended information than for unattended information. Second, there were age differences in visual statistical learning, but these differences were only observed for visual statistical learning of attended information. Third, stimulus category did not affect visual statistical learning of unattended information in older adults. Fourth, visual statistical learning occurs with awareness of statistical regularities. Further research is warranted to investigate the age-related mechanisms underlying visual statistical learning. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Are animates special? Exploring the effects of selective attention and animacy on visual statistical learning.

Our visual system is built to extract regularities in how objects in our visual environment appear in relation to each other across time and space ("visual statistical learning"). Existing research indicates that visual statistical learning is modulated by selective attention. Our attentional system prioritises information that enables adaptive behaviour; for example, animates are prioritised over inanimates (the "animacy advantage"). The present study examined the effects of selective attention and animacy on visual statistical learning in young adults (N = 284). We tested visual statistical learning of attended and unattended information across four animacy conditions: (1) living things that can self-initiate movement (animals); (2) living things that cannot self-initiate movement (fruits and vegetables); (3) non-living things that can generate movement (vehicles); and (4) non-living things that cannot generate movement (tools and kitchen utensils). We implemented a 4-point confidence rating scale as an assessment of participants' awareness of the regularities in the visual statistical learning task. There were four key findings. First, selective attention plays a critical role by modulating visual statistical learning. Second, animacy does not play a special role in visual statistical learning. Third, visual statistical learning of attended information cannot be exclusively accounted for by unconscious knowledge. Fourth, performance on the visual statistical learning task is associated with the proportion of stimuli that were named or labelled. Our findings support the notion that visual statistical learning is a powerful mechanism by which our visual system resolves an abundance of sensory input over time.

Exploiting test structure: case series, case-control comparison, and dissociation.

Most neuropsychological tests consist of multiple items, and a subject's test score is the sum of the item scores. The test results for each subject thus comprise multiple data-points, and any data-set with test results from more than one subject has at least a two-level structure, with the test item as the first level and the subject as the second level. This structure may be exploited to yield more nuanced statistical analyses than those that treat each subject's test score as a single data-point. Exploiting this structure allows us to take into account the effect of test length and dispersion on score variance and may enhance statistical power. Focusing on tests for which the score can be regarded as a binomial random variable, and using the binomial general linear model, we describe appropriate statistical methods for exploiting test structure in analysing a case series, comparing a case with a control sample, and testing for dissociation. These methods also allow multiple predictors, both categorical and continuous, to be taken into account, thereby enhancing the capacity of researchers to test hypotheses in a case series and to investigate other explanatory factors, in addition to case-control status.

Two hands are better than one: a new assessment method and a new interpretation of the non-visual illusion of self-touch.

A simple experimental paradigm creates the powerful illusion that one is touching one's own hand even when the two hands are separated by 15 cm. The participant uses her right hand to administer stimulation to a prosthetic hand while the Examiner provides identical stimulation to the participant's receptive left hand. Change in felt position of the receptive hand toward the prosthetic hand has previously led to the interpretation that the participant experiences self-touch at the location of the prosthetic hand, and experiences a sense of ownership of the prosthetic hand. Our results argue against this interpretation. We assessed change in felt position of the participant's receptive hand but we also assessed change in felt position of the participant's administering hand. Change in felt position of the administering hand was significantly greater than change in felt position of the receptive hand. Implications for theories of ownership are discussed.

Effects of Symmetry and Apparent Distance in a Parasagittal-Mirror Variant of the Rubber Hand Illusion Paradigm.

When I see my face in a mirror, its apparent position (behind the glass) is not one that my own face could be in. I accept the face I see as my own because I have an implicit understanding of how mirrors work. The situation is different if I look at the reflection of my right hand in a parasagittal mirror (parallel to body midline) when my left hand is hidden behind the mirror. It is as if I were looking through a window at my own left hand. The experience of body ownership has been investigated using rubber hand illusion (RHI) paradigms, and several studies have demonstrated ownership of a rubber hand viewed in a frontal mirror. Our "proof of concept" study was the first to combine use of a parasagittal mirror and synchronous stroking of both a prosthetic hand (viewed in the mirror) and the participant's hand, with a manipulation of distance between the hands. The strength of the RHI elicited by our parasagittal-mirror paradigm depended not on physical distance between the hands (30, 45, or 60 cm) but on apparent distance between the prosthetic hand (viewed in the mirror) and the participant's hand. This apparent distance was reduced to zero when the prosthetic hand and participant's hand were arranged symmetrically (e.g., 30 cm in front of and behind the mirror). Thus, the parasagittal-mirror paradigm may provide a distinctive way to assess whether competition for ownership depends on spatial separation between the prosthetic hand and the participant's hand.

Errors of somatosensory localisation in a patient with right-hemisphere stroke.

Following a right-hemisphere stroke, Patient NG could detect somatosensory stimulation that she was unable to localise. With vision precluded, NG systematically mislocalized touch on the little and ring finger of her affected left hand, and reported feeling this touch on the neighbouring rightward finger. This pattern of mislocalization occurred not only when the Examiner administered touch but also when touch was self-administered. We manipulated the relative position of NG's two hands during sensory assessment of the affected hand. When NG's right hand was positioned to the left of her affected hand, NG exhibited improved localisation. Theoretical and clinical implications are discussed.

Tactile expectations and the perception of self-touch: an investigation using the rubber hand paradigm.

The rubber hand paradigm is used to create the illusion of self-touch, by having the participant administer stimulation to a prosthetic hand while the Examiner, with an identical stimulus (index finger, paintbrush or stick), administers stimulation to the participant's hand. With synchronous stimulation, participants experience the compelling illusion that they are touching their own hand. In the current study, the robustness of this illusion was assessed using incongruent stimuli. The participant used the index finger of the right hand to administer stimulation to a prosthetic hand while the Examiner used a paintbrush to administer stimulation to the participant's left hand. The results indicate that this violation of tactile expectations does not diminish the illusion of self-touch. Participants experienced the illusion despite the use of incongruent stimuli, both when vision was precluded and when visual feedback provided clear evidence of the tactile mismatch.

Keeping an eye on visual search patterns in visuospatial neglect: A systematic review.

Patients with visuospatial neglect exhibit a failure to detect, respond, or orient towards information located in the side of space opposite to their brain lesion. To extend our understanding of the underlying cognitive processes involved in neglect, some studies have used eye movement measurements to complement behavioural data. We provide a qualitative synthesis of studies that have used eye-tracking in patients with neglect, with a focus on highlighting the utility of examining eye movements and reporting what eye-tracking has revealed about visual search patterns in these patients. This systematic review includes twenty studies that met the eligibility criteria. We extracted information pertaining to patient characteristics (e.g., age, type of stroke, time since stroke), neglect test(s) used, type of stimuli (e.g., static, dynamic), eye-tracker specifications (e.g., temporal and spatial resolution), and eye movement measurements (e.g., saccade amplitude, fixation duration). Five key themes were identified. First, eye-tracking is a useful tool to complement pen-and-paper neglect tests. Second, the lateral asymmetrical bias in eye movement patterns observed during active exploration also occurred while at rest. Third, the lateral asymmetrical bias was evident not only in the horizontal plane but also in the vertical plane. Fourth, eye movement patterns were modulated by stimulus- and task-related factors (e.g., visual salience, local perceptual features, image content, stimulus duration, presence of distractors). Fifth, measuring eye movements in patients with neglect is useful for determining and understanding other cognitive impairments, such as spatial working memory. To develop a fuller, and a more accurate, picture of neglect, future research would benefit from eye movement measurements.

Human hippocampal CA3 damage disrupts both recent and remote episodic memories.

Neocortical-hippocampal interactions support new episodic (event) memories, but there is conflicting evidence about the dependence of remote episodic memories on the hippocampus. In line with systems consolidation and computational theories of episodic memory, evidence from model organisms suggests that the cornu ammonis 3 (CA3) hippocampal subfield supports recent, but not remote, episodic retrieval. In this study, we demonstrated that recent and remote memories were susceptible to a loss of episodic detail in human participants with focal bilateral damage to CA3. Graph theoretic analyses of 7.0-Tesla resting-state fMRI data revealed that CA3 damage disrupted functional integration across the medial temporal lobe (MTL) subsystem of the default network. The loss of functional integration in MTL subsystem regions was predictive of autobiographical episodic retrieval performance. We conclude that human CA3 is necessary for the retrieval of episodic memories long after their initial acquisition and functional integration of the default network is important for autobiographical episodic memory performance.

Dissociations in rod bisection: the effect of viewing conditions on perception and action.

Research providing evidence from patients and neurologically healthy participants has demonstrated that visual perception can dissociate from visually guided actions, and that this dissociation can be removed by reducing visual feedback to a monocular view, or by completely occluding vision. Previously we have demonstrated a similar dissociation between perception and action on a rod-bisection task. The current paper examines whether manipulating the viewing conditions can also affect this dissociation. Forty-eight right-handed participants bisected five rods of different lengths, by pointing to the centre and by picking each up by the centre, under three viewing conditions: binocular viewing, monocular viewing and occluded viewing. Binocular viewing resulted in the expected perception-action dissociation: pointing bisection errors were to the right of centre and grasping bisection errors showed no bias. However, this pattern was also evident for the monocular-viewing condition, demonstrating that monocular viewing had no significant effect on bisection. In contrast, complete visual occlusion led to the elimination of the perception-action dissociation, and, in addition, the direction of the pointing errors reversed: both pointing and grasping errors were to the left of centre. These results are compared with a line-bisection task performed under similar conditions. This task resulted in consistent biases for which reducing visual feedback only influenced the extent of the error. The direction of the error was influenced by line position. These results demonstrate that theories for differential processing in the ventral and dorsal streams, used to elucidate perception-action dissociations, may not be compatible with the rod-bisection task and that online visuomotor feedback may better explain the dissociation.

Putting attention on the line: investigating the activation-orientation hypothesis of pseudoneglect.

Neurologically healthy participants systematically misbisect horizontal lines to the left of centre, a phenomenon termed 'pseudoneglect'. According to the activation-orientation hypothesis, the distribution of attention is biased in the direction opposite to the more activated hemisphere. Since visuospatial tasks involve activation of the right hemisphere, the hypothesis suggests that a leftward line-bisection bias might be explained by the uneven distribution of attention to the left and right line segments. A crucial assumption of this explanation is that the more attended half of the line will be perceived as longer than the less attended half. This study uses a tachistoscopic Landmark test and an attention cueing paradigm to explore this assumption. Three conditions were met to demonstrate the relative elongation of the more attended half of the line: (1) attention was biased to the cued end of the line, (2) subjective line midpoint was shifted towards the cued end, and (3) alternative biasing factors were ruled out. The results also demonstrate that increased hemispheric activation, resulting from presentation of stimuli in one or the other visual field, leads to subjective midpoints that are biased away from the more activated hemisphere.

The Phantom Vanish Magic Trick: Investigating the Disappearance of a Non-existent Object in a Dynamic Scene.

Drawing inspiration from sleight-of-hand magic tricks, we developed an experimental paradigm to investigate whether magicians' misdirection techniques could be used to induce the misperception of "phantom" objects. While previous experiments investigating sleight-of-hand magic tricks have focused on creating false assumptions about the movement of an object in a scene, our experiment investigated creating false assumptions about the presence of an object in a scene. Participants watched a sequence of silent videos depicting a magician performing with a single object. Following each video, participants were asked to write a description of the events in the video. In the final video, participants watched the Phantom Vanish Magic Trick, a novel magic trick developed for this experiment, in which the magician pantomimed the actions of presenting an object and then making it magically disappear. No object was presented during the final video. The silent videos precluded the use of false verbal suggestions, and participants were not asked leading questions about the objects. Nevertheless, 32% of participants reported having visual impressions of non-existent objects. These findings support an inferential model of perception, wherein top-down expectations can be manipulated by the magician to generate vivid illusory experiences, even in the absence of corresponding bottom-up information.