Biomedical subjects

John M Henderson

Publications and source records attributed to John M Henderson.

18 recordsLinked to original sources

PubMed2006

Cortical activation to indoor versus outdoor scenes: an fMRI study.

Prior studies identify two cortical areas, posterior parahippocampal cortex and retrosplenial cortex, that preferentially activate to images of real-world scenes compared to images of other meaningful visual stimuli such as objects and faces. Behavioral and computational studies suggest that sub-categories of real-world scenes differ in their visual and semantic properties. It is presently unknown whether the cortical areas that have been implicated in scene analysis similarly activate differentially to behaviorally relevant scene sub-categories. To examine this issue, we directly compared cortical activation to indoor and outdoor scenes in an fMRI study with a large number of non-repeated images in each condition. Activation in posterior parahippocampal cortex, including parahippocampal place area, was significantly greater for indoor than outdoor scenes. In contrast, no such difference was observed in retrosplenial cortex, though this region preferentially activated to scenes over faces. These findings suggest differences in function in these two areas. The results are consistent with the view that posterior parahippocampal cortex is functional in processing local space.

Adolescent↗

PubMed2006

Contextual guidance of eye movements and attention in real-world scenes: the role of global features in object search.

Many experiments have shown that the human visual system makes extensive use of contextual information for facilitating object search in natural scenes. However, the question of how to formally model contextual influences is still open. On the basis of a Bayesian framework, the authors present an original approach of attentional guidance by global scene context. The model comprises 2 parallel pathways; one pathway computes local features (saliency) and the other computes global (scene-centered) features. The contextual guidance model of attention combines bottom-up saliency, scene context, and top-down mechanisms at an early stage of visual processing and predicts the image regions likely to be fixated by human observers performing natural search tasks in real-world scenes.

Attention↗

PubMed2006

Contextual cueing in naturalistic scenes: Global and local contexts.

In contextual cueing, the position of a target within a group of distractors is learned over repeated exposure to a display with reference to a few nearby items rather than to the global pattern created by the elements. The authors contrasted the role of global and local contexts for contextual cueing in naturalistic scenes. Experiment 1 showed that learned target positions transfer when local information is altered but not when global information is changed. Experiment 2 showed that scene-target covariation is learned more slowly when local, but not global, information is repeated across trials than when global but not local information is repeated. Thus, in naturalistic scenes, observers are biased to associate target locations with global contexts.

Association Learning↗

PubMed2006

Attentional versus motor inhibition in adults with attention-deficit/hyperactivity disorder.

Faulty inhibition is theorized to be a central feature in attention-deficit/hyperactivity disorder (ADHD), but it remains unclear whether inhibitory impairments encompass both motoric and attentional domains. Further, characterization of inhibitory deficits in adults with ADHD is needed. We experimentally assessed adults who met diagnostic criteria for ADHD and a subgroup who had partially remitted. Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) subtype effects were also examined. Motoric inhibition was assessed with the antisaccade task, and attentional inhibition was assessed with the attentional blink (AB) task. Antisaccade results replicated prior findings of extended latencies and increased anticipatory saccades in ADHD. Errors, however, appeared to be epiphenomenal to ADHD as they were absent when symptoms had partially remitted. Anticipatory saccades appeared as potential core problems that remained even when symptoms had improved. Differential response patterns were found for predominantly inattentive and combined subtypes, with the latter showing increasing anticipatory movements with increasing fixation time. In the AB task, ADHD groups committed more errors but showed no convincing evidence of an abnormal blink. These results demonstrate clear effects on motoric inhibition but not attentional inhibition in adults with ADHD.

Adolescent↗

PubMed2006

Recognition and attention guidance during contextual cueing in real-world scenes: evidence from eye movements.

When confronted with a previously encountered scene, what information is used to guide search to a known target? We contrasted the role of a scene's basic-level category membership with its specific arrangement of visual properties. Observers were repeatedly shown photographs of scenes that contained consistently but arbitrarily located targets, allowing target positions to be associated with scene content. Learned scenes were then unexpectedly mirror reversed, spatially translating visual features as well as the target across the display while preserving the scene's identity and concept. Mirror reversals produced a cost as the eyes initially moved toward the position in the display in which the target had previously appeared. The cost was not complete, however; when initial search failed, the eyes were quickly directed to the target's new position. These results suggest that in real-world scenes, shifts of attention are initially based on scene identity, and subsequent shifts are guided by more detailed information regarding scene and object layout.

Attention↗

PubMed2005

Executive functions and ADHD in adults: evidence for selective effects on ADHD symptom domains.

Dual-process models of attention-deficit/hyperactivity disorder (ADHD) suggest that both executive functioning and regulatory functions (e.g., processing speed) are involved and that executive function weaknesses may be associated specifically with symptoms of inattention-disorganization but not hyperactivity-impulsivity. Adults aged 18-37 (105 with ADHD, 90 controls) completed a neuropsychological battery. The ADHD group had weaker performance than did the control group (p<.01) on both executive and speed measures. Symptoms of inattention-disorganization were uniquely related to executive functioning with hyperactivity-impulsivity controlled. Inattention was associated with slower response speed, and hyperactivity-impulsivity with faster output speed. Results were not accounted for by IQ, age, gender, education level, or comorbid disorders. Findings are discussed in terms of developmental and dual-process models of ADHD leading into adulthood.

Adolescent↗

PubMed2005

The role of saccade targeting in the transsaccadic integration of object types and tokens.

The presence of location-dependent and location-independent benefits on object identification in an eye movement contingent preview paradigm has been taken as support for the transsaccadic integration of object types and object tokens (J. M. Henderson, 1994). A recent study, however, suggests a critical role for saccade targeting in the generation of the 2 preview effects (F. Germeys, De Graef, & Verfaillie, 2002). In the present study, eye movements were monitored in a preview paradigm, and both location-independent and location-dependent preview benefits were observed regardless of the saccade target status of the preview object. The findings support the view that type and token representational systems contribute independently to the integration of object information across eye movements.

Form Perception↗

PubMed2005

Prioritization of new objects in real-world scenes: evidence from eye movements.

The authors examined the prioritization of abruptly appearing objects in real-world scenes by measuring the eyes' propensity to be directed to the new object. New objects were fixated more often than chance whether they appeared during fixations (transient onsets) or saccades (nontransient onsets). However, onsets that appeared during fixations were fixated sooner and more often than those coincident with saccades. Prioritization of onsets during saccades, but not fixations, were affected by manipulations of memory: Reducing scene viewing time prior to the onset eliminated prioritization, whereas prior study of the scenes increased prioritization. Transient objects draw attention quickly and do not depend on memory, but without a transient signal, new objects are prioritized over several saccades as memory is used to explicitly identify the change. These effects were not modulated by observers' expectations concerning the appearance of new objects, suggesting the prioritization of a transient is automatic and that memory-guided prioritization is implicit.

Attention↗

PubMed2005

Incidental visual memory for targets and distractors in visual search.

We explored incidental retention of visual details of encountered objects during search. Participants searched for conjunction targets in 32 arrays of 12 pictures of real-world objects and then performed a token discrimination task that examined their memory for visual details of the targets and distractors from the search task. The results indicate that even though participants had not been instructed to memorize the objects, the visual details of search targets and distractor objects related to the targets were retained after the search. Distractor objects unrelated to the search target were remembered more poorly. Eye-movement measures indicated that the objects that were remembered were looked at more frequently during search than those that were not remembered. These results provide support that detailed visual information is included incidentally in the visual representation of an object after the object is no longer in view.

Attention↗

PubMed2005

Eye movements are functional during face learning.

In a free viewing learning condition, participants were allowed to move their eyes naturally as they learned a set of new faces. In a restricted viewing learning condition, participants remained fixated in a single central location as they learned the new faces. Recognition of the learned faces was then tested following the two learning conditions. Eye movements were recorded during the free viewing learning condition, as well as during recognition. The recognition results showed a clear deficit following the restricted viewing condition, compared with the free viewing condition, demonstrating that eye movements play a functional role during human face learning. Furthermore, the features selected for fixation during recognition were similar following free viewing and restricted viewing learning, suggesting that the eye movements generated during recognition are not simply a recapitulation of those produced during learning.

Eye Movements↗

PubMed2005

Object appearance, disappearance, and attention prioritization in real-world scenes.

We examined the prioritization of abruptly appearing and disappearing objects in real-world scenes. These scene changes occurred either during a fixation (transient appearance/disappearance) or during a saccade (nontransient appearance/disappearance). Prioritization was measured by the eyes' propensity to be directed to the region of the scene change. Object additions and deletions were fixated at rates greater than chance, suggesting that both types of scene change arecues used by the visual system to guide attention during scene exploration, although appearances were fixated twice as often as disappearances, indicating that new objects are more salient than deleted objects. New and deleted objects were prioritized sooner and more frequently if they occurred during a fixation, as compared with during a saccade, indicating an important role of the transient signal that often accompanies sudden changes in scenes. New objects were prioritized regardless of whether they appeared during a fixation or a saccade, whereas prioritization of a deleted object occurred only if (1) a transient signal was present or (2) the removal of the object revealed previously occluded objects.

Attention↗

PubMed2004

Sustained change blindness to incremental scene rotation: a dissociation between explicit change detection and visual memory.

In a change detection paradigm, the global orientation of a natural scene was incrementally changed in 1 degree intervals. In Experiments 1 and 2, participants demonstrated sustained change blindness to incremental rotation, often coming to consider a significantly different scene viewpoint as an unchanged continuation of the original view. Experiment 3 showed that participants who failed to detect the incremental rotation nevertheless reliably detected a single-step rotation back to the initial view. Together, these results demonstrate an important dissociation between explicit change detection and visual memory. Following a change, visual memory is updated to reflect the changed state of the environment, even if the change was not detected.

Humans↗

PubMed2003

Human gaze control during real-world scene perception.

In human vision, acuity and color sensitivity are best at the point of fixation, and the visual-cognitive system exploits this fact by actively controlling gaze to direct fixation towards important and informative scene regions in real time as needed. How gaze control operates over complex real-world scenes has recently become of central concern in several core cognitive science disciplines including cognitive psychology, visual neuroscience, and machine vision. This article reviews current approaches and empirical findings in human gaze control during real-world scene perception.

Journal Article↗

PubMed2003

Global transsaccadic change blindness during scene perception.

Each time the eyes are spatially reoriented via a saccadic eye movement, the image falling on the retina changes. How visually specific are the representations that are functional across saccades during active scene perception? This question was investigated with a saccade-contingent display-change paradigm in which pictures of complex real-world scenes were globally changed in real time during eye movements. The global changes were effected by presenting each scene as an alternating set of scene strips and occluding gray bars, and by reversing the strips and bars during specific saccades. The results from two experiments demonstrated a global transsaccadic change-blindness effect, suggesting that point-by-point visual representations are not functional across saccades during complex scene perception.

Adult↗

PubMed2003

Eye movements and visual memory: detecting changes to saccade targets in scenes.

Saccade-contingent change detection provides a powerful tool for investigating scene representation and scene memory. In the present study, critical objects presented within color images of naturalistic scenes were changed during a saccade toward or away from the target. During the saccade,the critical object was changed to another object type, to a visually different token of the same object type, or was deleted from the scene. There were three main results. First, the deletion of a saccade target was special: Detection performance for saccade target deletions was very good, and this level of performance did not decline with the amplitude of the saccade. In contrast, detection of type and token changes at the saccade target, and of all changes including deletions at a location that had just been fixated but was not the saccade target, decreased as the amplitude of the saccade increased. Second, detection performance for type and token changes, both when the changing object was the target of the saccade and when the object had just been fixated but was not the saccade target, was well above chance. Third, mean gaze durations were reliably elevated for those trials in which the change was not overtly detected. The results suggest that the presence of the saccade target plays a special role in trassaccadic integration, and together with other recent findings, suggest more generally that a relatively rich scene representation is retained across saccades and stored in visual memory.

Fixation, Ocular↗

PubMed2003

Eye movements and picture processing during recognition.

Eye movements were monitored during a recognition memory test of previously studied pictures of full-color scenes. The test scenes were identical to the originals, had an object deleted from them, or included a new object substituted for an original object. In contrast to a prior report (Parker, 1978), we found no evidence that object deletions or substitutions could be recognized on the basis of information acquired from the visual periphery. Deletions were difficult to recognize peripherally, and the eyes were not attracted to them. Overall, the amplitude of the average saccade to the critical object during the memory test was less than 4.5 degrees of visual angle in all conditions and averaged 4.1 degrees across conditions. We conclude that information about object presence and identity in a scene is limited to a relatively small region around the current fixation point.

Color Perception↗

PubMed2003

Testing a conceptual locus for the inconsistent object change detection advantage in real-world scenes.

Changes to objects that are inconsistent with the scene in which they appear are detected more accurately than changes to consistent objects. In three experiments, we tested whether this inconsistent object advantage derives from the differential retention of conceptual codes generated from a brief view of a real-world scene in accordance with a conceptual short-term memory (CSTM) hypothesis. A scene was presented for 250 msec, followed by a brief mask and a test scene in which a target object was either changed or not changed. In Experiment 1, changes that altered conceptual content (object deletion) were contrasted with visual changes (left-right orientation changes). In Experiment 2, the duration of the mask was manipulated to vary the amount of time available for conceptual consolidation of the initial scene. In Experiment 3, the type of mask was manipulated: Either a meaningless pattern mask or a meaningful, and thus conceptually disruptive, scene was shown. The inconsistent object advantage was obtained in each experiment, yet in none was it modulated in the direction predicted by the CSTM hypothesis. Instead, the inconsistent object advantage is likely to be caused by contextual influence on memory for visual object representations.

Discrimination, Psychological↗

PubMed2002

Inhibitory processes in adults with persistent childhood onset ADHD.

The theory that attention-deficit/hyperactivity disorder (ADHD) stems from a deficit in an executive behavioral inhibition process has been little studied in adults, where the validity of ADHD is in debate. This study examined, in high-functioning young adults with persistent ADHD and a control group, 2 leading measures of inhibitory control: the antisaccad task and the negative priming task. ADHD adults showed weakened ability to effortfully stop a refle ve or anticipated oculomotor response but had normal ability to automatically suppress irrelevant information. Results suggest that an inhibitory deficit in ADHD is confined to effortful inhibition of motor response, that antisaccade and negative priming tasks index distinct inhibition systems, and that persistence of ADHD symptoms into adulthood is associated with persistence of executive motor inhibition deficits.

Adult↗