“Motor Oblique Effect”: Perceptual Direction Discrimination and Pointing to Memorized Visual Targets Share the Same Preference for Cardinal Orientations

2007 ◽  
Vol 97 (2) ◽  
pp. 1068-1077 ◽  
Author(s):  
Nikolaos Smyrnis ◽  
Asimakis Mantas ◽  
Ioannis Evdokimidis
Keyword(s):  
Visual Target ◽  
Motor Task ◽  
Oblique Effect ◽  
Quadratic Function ◽  
Initial Direction ◽  
Direction Discrimination ◽  
Pointing Movements ◽  
Equivalent Measure ◽  
Visual Targets ◽  
Target Locations

In previous studies we observed a pattern of systematic directional errors when humans pointed to memorized visual target locations in two-dimensional (2-D) space. This directional error was also observed in the initial direction of slow movements toward visual targets or movements to kinesthetically defined targets in 2-D space. In this study we used a perceptual experiment where subjects decide whether an arrow points in the direction of a visual target in 2-D space and observed a systematic distortion in direction discrimination known as the “oblique effect.” More specifically, direction discrimination was better for cardinal directions than for oblique. We then used an equivalent measure of direction discrimination in a task where subjects pointed to memorized visual target locations and showed the presence of a motor oblique effect. We finally modeled the oblique effect in the perceptual and motor task using a quadratic function. The model successfully predicted the observed direction discrimination differences in both tasks and, furthermore, the parameter of the model that was related to the shape of the function was not different between the motor and the perceptual tasks. We conclude that a similarly distorted representation of target direction is present for memorized pointing movements and perceptual direction discrimination.

scholarly journals A bimodal extension of the Eriksen flanker task

2020 ◽  
Author(s):  
Rolf Ulrich ◽  
Laura Prislan ◽  
Jeff Miller
Keyword(s):  
Visual Target ◽  
Target Item ◽  
Flanker Task ◽  
Response Competition ◽  
Relevant Information ◽  
Irrelevant Information ◽  
Flanker Effect ◽  
Starting Point ◽  
Visual Targets ◽  
Task Irrelevant

Abstract The Eriksen flanker task is a traditional conflict paradigm for studying the influence of task-irrelevant information on the processing of task-relevant information. In this task, participants are asked to respond to a visual target item (e.g., a letter) that is flanked by task-irrelevant items (e.g., also letters). Responses are typically faster and more accurate when the task-irrelevant information is response-congruent with the visual target than when it is incongruent. Several researchers have attributed the starting point of this flanker effect to poor selective filtering at a perceptual level (e.g., spotlight models), which subsequently produces response competition at post-perceptual stages. The present study examined whether a flanker-like effect could also be established within a bimodal analog of the flanker task with auditory irrelevant letters and visual target letters, which must be processed along different processing routes. The results of two experiments revealed that a flanker-like effect is also present with bimodal stimuli. In contrast to the unimodal flanker task, however, the effect only emerged when flankers and targets shared the same letter name, but not when they were different letters mapped onto the same response. We conclude that the auditory flankers can influence the time needed to recognize visual targets but do not directly activate their associated responses.

Dependence of Saccade-Related Activity in the Primate Superior Colliculus on Visual Target Presence

2001 ◽  
Vol 86 (2) ◽  
pp. 676-691 ◽  
Author(s):  
Jay A. Edelman ◽  
Michael E. Goldberg
Keyword(s):  
Superior Colliculus ◽  
Visual Target ◽  
Visual Response ◽  
Target Presence ◽  
Related Activity ◽  
Intermediate Layers ◽  
Saccade Velocity ◽  
Trial Basis ◽  
Visual Targets ◽  
Extracellular Activity

Neurons in the intermediate layers of the superior colliculus respond to visual targets and/or discharge immediately before and during saccades. These visual and motor responses have generally been considered independent, with the visual response dependent on the nature of the stimulus, and the saccade-related activity related to the attributes of the saccade, but not to how the saccade was elicited. In these experiments we asked whether saccade-related discharge in the superior colliculus depended on whether the saccade was directed to a visual target. We recorded extracellular activity of neurons in the intermediate layers of the superior colliculus of three rhesus monkeys during saccades in tasks in which we varied the presence or absence of a visual target and the temporal delays between the appearance and disappearance of a target and saccade initiation. Across our sample of neurons ( n = 64), discharge was highest when a saccade was made to a still-present visual target, regardless of whether the target had recently appeared or had been present for several hundred milliseconds. Discharge was intermediate when the target had recently disappeared and lowest when the target had never appeared during that trial. These results are consistent with the hypothesis that saccade-related discharge decreases as the time between the target disappearance and saccade initiation increases. Saccade velocity was also higher for saccades to visual targets, and correlated on a trial-by-trial basis with perisaccadic discharge for many neurons. However, discharge of many neurons was dependent on task but independent of saccade velocity, and across our sample of neurons, saccade velocity was higher for saccades made immediately after target appearance than would be predicted by discharge level. A tighter relationship was found between saccade precision and perisaccadic discharge. These findings suggest that just as the purpose of the saccadic system in primates is to drive the fovea to a visual target, presaccadic motor activity in the superior colliculus is most intense when such a target is actually present. This enhanced activity may, itself, contribute to the enhanced performance of the saccade system when the saccade is made to a real visual target.

Interactions between Voluntary and Stimulus-driven Spatial Attention Mechanisms across Sensory Modalities

2009 ◽  
Vol 21 (12) ◽  
pp. 2384-2397 ◽  
Author(s):  
Valerio Santangelo ◽  
Marta Olivetti Belardinelli ◽  
Charles Spence ◽  
Emiliano Macaluso
Keyword(s):  
Spatial Attention ◽  
Auditory Stimulus ◽  
Attentional Control ◽  
Spatial Information ◽  
Visual Target ◽  
Exogenous Attention ◽  
Physiological Basis ◽  
Sensory Modalities ◽  
Visual Targets ◽  
Task Irrelevant

In everyday life, the allocation of spatial attention typically entails the interplay between voluntary (endogenous) and stimulus-driven (exogenous) attention. Furthermore, stimuli in different sensory modalities can jointly influence the direction of spatial attention, due to the existence of cross-sensory links in attentional control. Using fMRI, we examined the physiological basis of these interactions. We induced exogenous shifts of auditory spatial attention while participants engaged in an endogenous visuospatial cueing task. Participants discriminated visual targets in the left or right hemifield. A central visual cue preceded the visual targets, predicting the target location on 75% of the trials (endogenous visual attention). In the interval between the endogenous cue and the visual target, task-irrelevant nonpredictive auditory stimuli were briefly presented either in the left or right hemifield (exogenous auditory attention). Consistent with previous unisensory visual studies, activation of the ventral fronto-parietal attentional network was observed when the visual targets were presented at the uncued side (endogenous invalid trials, requiring visuospatial reorienting), as compared with validly cued targets. Critically, we found that the side of the task-irrelevant auditory stimulus modulated these activations, reducing spatial reorienting effects when the auditory stimulus was presented on the same side as the upcoming (invalid) visual target. These results demonstrate that multisensory mechanisms of attentional control can integrate endogenous and exogenous spatial information, jointly determining attentional orienting toward the most relevant spatial location.

scholarly journals Failure to use corollary discharge to remap visual target locations is associated with psychotic symptom severity in schizophrenia

2015 ◽  
Vol 114 (2) ◽  
pp. 1129-1136 ◽  
Author(s):  
Lara Rösler ◽  
Martin Rolfs ◽  
Stefan van der Stigchel ◽  
Sebastiaan F. W. Neggers ◽  
Wiepke Cahn ◽  
...  
Keyword(s):  
Symptom Severity ◽  
Target Location ◽  
Visual Target ◽  
Saccadic Eye Movements ◽  
Landing Site ◽  
Corollary Discharge ◽  
Psychotic Symptoms ◽  
Healthy Controls ◽  
Visual Stability ◽  
Target Locations

Corollary discharge (CD) refers to “copies” of motor signals sent to sensory areas, allowing prediction of future sensory states. They enable the putative mechanisms supporting the distinction between self-generated and externally generated sensations. Accordingly, many authors have suggested that disturbed CD engenders psychotic symptoms of schizophrenia, which are characterized by agency distortions. CD also supports perceived visual stability across saccadic eye movements and is used to predict the postsaccadic retinal coordinates of visual stimuli, a process called remapping. We tested whether schizophrenia patients (SZP) show remapping disturbances as evidenced by systematic transsaccadic mislocalizations of visual targets. SZP and healthy controls (HC) performed a task in which a saccadic target disappeared upon saccade initiation and, after a brief delay, reappeared at a horizontally displaced position. HC judged the direction of this displacement accurately, despite spatial errors in saccade landing site, indicating that their comparison of the actual to predicted postsaccadic target location relied on accurate CD. SZP performed worse and relied more on saccade landing site as a proxy for the presaccadic target, consistent with disturbed CD. This remapping failure was strongest in patients with more severe psychotic symptoms, consistent with the theoretical link between disturbed CD and phenomenological experiences in schizophrenia.

scholarly journals Experience-dependent increases in sharp-wave ripples near visual targets

2016 ◽  
Author(s):  
Timothy K. Leonard ◽  
Kari L. Hoffman
Keyword(s):  
Visual Target ◽  
Visual Exploration ◽  
Goal Location ◽  
Sharp Wave ◽  
Temporal Properties ◽  
Visual Targets ◽  
Past Experiences

We measured hippocampal sharp-wave ripples during goal-directed visual exploration in macaques. Exploratory sharp-wave ripples were more frequent on familiar trials, in the second half of search, and near the visual target (i.e., the goal location). These spatial and temporal properties may help SWRs coordinate hippocampal and extra-hippocampal firing sequences that guide actions based on past experiences.

Effects of Noise Intensity on Visual Target-Detection Performance

1972 ◽  
Vol 14 (2) ◽  
pp. 181-185 ◽  
Author(s):  
Harold D. Warneb ◽  
Norman W. Heimstra
Keyword(s):  
Target Detection ◽  
Noise Intensity ◽  
Target Location ◽  
Visual Target ◽  
Visual Display ◽  
Detection Performance ◽  
Difficulty Level ◽  
Intensity Level ◽  
Detection Error ◽  
Target Locations

The purpose of the present study was to determine the effects of continuous white noise on visual target-detection performance. The variables manipulated were noise-intensity level, display-difficulty level, and target location. Four noise levels were utilized: 0, 80, 90, and 100 db. The 0-db. level served as the control condition. Display difficulty was defined in terms of the number of nontarget, or background, display elements. Three levels of difficulty were used: 8, 16, and 32 background letter characters. The target locations examined were the central and peripheral regions of the visual display. Twenty subjects were tested under all conditions. Both detection time and detection error were recorded. The results indicated that noise-intensity and display-difficulty level were significantly interrelated with respect to detection speed but not to detection error.

scholarly journals Simulations of Saccade Curvature by Models That Place Superior Colliculus Upstream From the Local Feedback Loop

2005 ◽  
Vol 93 (4) ◽  
pp. 2354-2358 ◽  
Author(s):  
Mark M. G. Walton ◽  
David L. Sparks ◽  
Neeraj J. Gandhi
Keyword(s):  
Superior Colliculus ◽  
Brain Stem ◽  
Feedback Loop ◽  
Two Dimensional ◽  
Initial Direction ◽  
Relative Level ◽  
Level Of Activity ◽  
Local Feedback ◽  
Visual Targets ◽  
The Brain

When humans or monkeys are asked to make saccades to visual targets accompanied by one or more distractors, the two dimensional trajectory of the saccade will sometimes display significant curvature. Port and Wurtz used dual electrode recordings to show that this phenomenon is associated with activity at more than one site in superior colliculus (SC). The timing and initial direction of the curvature could be predicted by computing a weighted vector average of the normalized activity of the two neurons. As these authors noted, however, this approach does not result in correct predictions of the final direction of curved saccades. We show that the final direction of these movements can be predicted by taking into account the brain stem saccade generator and the local feedback loop. If the output of SC is computed as a weighted vector average of the saccades requested by the activated sites, and this collicular output is interpreted by downstream structures as desired displacement, existing models that place SC upstream from the local feedback loop can generate realistic saccade trajectories, including the final direction. We propose that saccade curvature is the result of a change in the relative level of activity at the two sites, which the brain stem saccade generator interprets as a change in desired displacement.

scholarly journals The Intraparietal Cortex: Subregions Involved in Fixation, Saccades, and in the Visual and Somatosensory Guidance of Reaching

2001 ◽  
Vol 21 (6) ◽  
pp. 671-682 ◽  
Author(s):  
Georgia G. Gregoriou ◽  
Helen E. Savaki
Keyword(s):  
Visual Information ◽  
Cortical Area ◽  
Visual Target ◽  
Proprioceptive Information ◽  
Somatosensory Information ◽  
Area 7 ◽  
Area 5 ◽  
Visual Targets ◽  
Straight Ahead ◽  
Deoxyglucose Method

The functional activity of the intraparietal cortex was mapped with the [14C]deoxyglucose method in monkeys performing fixation of a central visual target, saccades to visual targets, reaching in the light during fixation of a central visual target, and acoustically triggered reaching in the dark while the eyes maintained a straight ahead direction. Different subregions of the intraparietal cortical area 7 were activated by fixation, saccades to visual targets, and acoustically triggered reaching in the dark. Subregions in the ventral part of the intraparietal cortex (around the fundus of the intraparietal sulcus) were activated only during reaching in the light, in which case visual information was available to guide the moving forelimb. In contrast, subregions in the dorsal part of the intraparietal cortical area 5 were activated during both reaching in the light and the dark, in which cases somatosensory information was the only one available in common. Thus, visual guidance of reaching is associated with the ventral intraparietal cortex, whereas somatosensory guidance, based on proprioceptive information about the current forelimb position, is associated with dorsal intraparietal area 5.

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