Orientation Change Detection Research Articles

Alpha and SSVEP power outperform gamma power in capturing attentional modulation in human EEG.

Attention typically reduces power in the alpha (8-12Hz) band and increases power in gamma (>30Hz) band in brain signals, as reported in macaque local field potential (LFP) and human electro/magneto-encephalogram (EEG/MEG) studies. In addition, EEG studies often use flickering stimuli that produce a specific measure called steady-state-visually-evoked-potential (SSVEP), whose power also increases with attention. However, effectiveness of these neural measures in capturing attentional modulation is unknown since stimuli and task paradigms vary widely across studies. In a recent macaque study, attentional modulation was more salient in the gamma band of the LFP, compared to alpha or SSVEP. To compare this with human EEG, we designed an orientation change detection task where we presented both static and counterphasing stimuli of matched difficulty levels to 26 subjects and compared attentional modulation of various measures under similar conditions. We report two main results. First, attentional modulation was comparable for SSVEP and alpha. Second, non-foveal stimuli produced weak gamma despite various stimulus optimizations and showed negligible attentional modulation although full-screen gratings showed robust gamma activity. Our results are useful for brain-machine-interfacing studies where suitable features are used for decoding attention, and also provide clues about spatial scales of neural mechanisms underlying attention.

Familiar objects benefit more from transsaccadic feature predictions.

The transsaccadic feature prediction mechanism associates peripheral and foveal information belonging to the same object to make predictions about how an object seen in the periphery would appear in the fovea or vice versa. It is unclear if such transsaccadic predictions require experience with the object such that only familiar objects benefit from this mechanism by virtue of having peripheral-foveal associations. In two experiments, we tested whether familiar objects have an advantage over novel objects in peripheral-foveal matching and transsaccadic change detection tasks. In both experiments, observers were unknowingly familiarized with a small set of stimuli by completing a sham orientation change detection task. In the first experiment, observers subsequently performed a peripheral-foveal matching task, where they needed to pick the foveal test object that matched a briefly presented peripheral target. In the second experiment, observers subsequently performed a transsaccadic object change detection task where a peripheral target was exchanged or not exchanged with another target after the saccade, either immediately or after a 300-ms blank period. We found an advantage of familiar objects over novel objects in both experiments. While foveal-peripheral associations explained the familiarity effect in the matching task of the first experiment, the second experiment provided evidence for the advantage of peripheral-foveal associations in transsaccadic object change detection. Introducing a postsaccadic blank improved change detection performance in general but more for familiar than for novel objects. We conclude that familiar objects benefit from additional object-specific predictions.

The motion silencing effect in static and dynamic orientation change detection

The motion silencing effect in static and dynamic orientation change detection

The Neural Mechanism Underlying Visual Working Memory Training and Its Limited Transfer Effect.

Visual working memory (VWM) training has been shown to improve performance in trained tasks with limited transfer to untrained tasks. The neural mechanism underlying this limited transfer remains unknown. In the present study, this issue was addressed by combining model-fitting methods with EEG recordings. Participants were trained on a color delay estimation task for 12 consecutive 1-hr sessions, and the transfer effect was evaluated with an orientation change detection task. The EEG responses during both tasks were collected in a pretraining test, a posttraining test conducted 1 day after training, and a follow-up test conducted 3 months after training. According to our model-fitting results, training significantly improved the capacity but not the precision of color working memory (WM), and this capacity improvement did not transfer to the orientation change detection task, spatial 2-back task, symmetry span task, or Raven reasoning test. The EEG results revealed that training resulted in a specific and sustained increase in parietal theta power suppression in the color WM task, which reflected individual color WM capacity. In contrast, the increase in parietal-temporal alpha power, which reflected individual orientation WM capacity, did not change with training. Together, these findings suggest that the simultaneous change of stimulus type and task structure would modulate the cognitive and neural substrates of WM tasks and introduce additional constraints for the transfer of WM training.

A horizontal–vertical anisotropy in spatial short-term memory

ABSTRACT Visual perception and saccadic eye-movements are more precise when directed at isoeccentric locations along the horizontal compared to vertical meridian. This effect is known as horizontal-vertical anisotropy (HVA). Given that the eye-movement system plays an important role in spatial short-term memory (STM) it was hypothesized that spatial STM would also show a horizontal-vertical anisotropy. Consistent with this hypothesis an online experiment revealed a significant HVA in spatial STM (Experiment 1). This effect persisted even when eye-movements were precluded by using very short display durations (Experiment 2). However, there was no HVA in a colour span or orientation change detection task. It is argued that the HVA in spatial STM may result from greater imprecision in the representation of spatial locations along the vertical meridian relative to the horizontal meridian in the spatial maps underpinning spatial STM, a bilateral field advantage, or some combination of these mechanisms.

Uncertainty is maintained and used in working memory.

What are the contents of working memory? In both behavioral and neural computational models, a working memory representation is typically described by a single number, namely, a point estimate of a stimulus. Here, we asked if people also maintain the uncertainty associated with a memory and if people use this uncertainty in subsequent decisions. We collected data in a two-condition orientation change detection task; while both conditions measured whether people used memory uncertainty, only one required maintaining it. For each condition, we compared an optimal Bayesian observer model, in which the observer uses an accurate representation of uncertainty in their decision, to one in which the observer does not. We find that this “Use Uncertainty” model fits better for all participants in both conditions. In the first condition, this result suggests that people use uncertainty optimally in a working memory task when that uncertainty information is available at the time of decision, confirming earlier results. Critically, the results of the second condition suggest that this uncertainty information was maintained in working memory. We test model variants and find that our conclusions do not depend on our assumptions about the observer's encoding process, inference process, or decision rule. Our results provide evidence that people have uncertainty that reflects their memory precision on an item-specific level, maintain this information over a working memory delay, and use it implicitly in a way consistent with an optimal observer. These results challenge existing computational models of working memory to update their frameworks to represent uncertainty.

Motion disrupts dynamic visual search for an orientation change

Visual search in dynamic environments, for example lifeguarding or CCTV monitoring, has several fundamentally different properties to standard visual search tasks. The visual environment is constantly moving, a range of items could become targets and the task is to search for a certain event. We developed a novel task in which participants were required to search static and moving displays for an orientation change thus capturing components of visual search, multiple object tracking and change detection paradigms. In Experiment 1, we found that the addition of moving distractors slowed participants’ response time to detect an orientation changes in a moving target, showing that the motion of distractors disrupts the rapid detection of orientation changes in a moving target. In Experiment 2 we found that, in displays of both moving and static objects, response time was slower if a moving object underwent a change than if a static object did, thus demonstrating that motion of the target itself also disrupts the detection of an orientation change. Our results could have implications for training in real-world occupations where the task is to search a dynamic environment for a critical event. Moreover, we add to the literature highlighting the need to develop lab-based tasks with high experimental control from any real-world tasks researchers may wish to investigate rather than extrapolating from static visual search tasks to more dynamic environments.

The Nature of Haptic Working Memory Capacity and Its Relation to Visual Working Memory

Abstract I conducted three experiments to investigate haptic working memory capacity using a haptic change detection task with 2D stimuli. I adopted a single-task paradigm comprising haptic single-feature (orientation or texture) and haptic multifeature (orientation and texture) conditions in Experiment 1 and a dual-task paradigm with a primary haptic orientation or texture change detection task and a concurrent secondary visual shape or colour change detection task in Experiments 2–3. I observed that in the single-task paradigm, haptic change detection capacity was higher for single features than it was for multiple features. In haptic working memory, unlike in visual working memory, features of two different dimensions within an object cannot be integrated. In the dual-task paradigm, interference was observed when the concurrent visual shape change detection task was combined with the haptic orientation change detection task although interference was not observed when the concurrent visual colour change detection task was combined with it. In addition, the concurrent visual shape or colour change detection task did not interfere with the capacity for haptic texture memory, which was higher than that for haptic orientation memory. These findings demonstrate that geometric properties perhaps retained a common storage system shared between haptic working memory and visual working memory; however, haptic texture might be retained in an independent stable storage system that is haptic-specific.

A Causal Role for Mouse Superior Colliculus in Visual Perceptual Decision-Making.

The superior colliculus (SC) is arguably the most important visual structure in the mouse brain and is well known for its involvement in innate responses to visual threats and prey items. In other species, the SC plays a central role in voluntary as well as innate visual functions, including crucial contributions to selective attention and perceptual decision-making. In the mouse, the possible role of the SC in voluntary visual choice behaviors has not been established. Here, we demonstrate that the mouse SC of both sexes plays a causal role in visual perceptual decision-making by transiently inhibiting SC activity during an orientation change detection task. First, unilateral SC inhibition-induced spatially specific deficits in detection. Hit rates were reduced, and reaction times increased for orientation changes in the contralateral but not ipsilateral visual field. Second, the deficits caused by SC inhibition were specific to a temporal epoch coincident with early visual burst responses in the SC. Inhibiting SC during this 100-ms period caused a contralateral detection deficit, whereas inhibition immediately before or after did not. Third, SC inhibition reduced visual detection sensitivity. Psychometric analysis revealed that inhibiting SC visual activity significantly increased detection thresholds for contralateral orientation changes. In addition, effects on detection thresholds and lapse rates caused by SC inhibition were larger in the presence of a competing visual stimulus, indicating a role for the mouse SC in visual target selection. Together, our results demonstrate that the mouse SC is necessary for the normal performance of voluntary visual choice behaviors.SIGNIFICANCE STATEMENT The mouse superior colliculus (SC) has become a popular model for studying the circuit organization and development of the visual system. Although the SC is a fundamental component of the visual pathways in mice, its role in visual perceptual decision-making is not clear. By investigating how temporally precise SC inhibition influenced behavioral performance during a visually guided orientation change detection task, we identified a 100-ms temporal epoch of SC visual activity that is crucial for the ability of mice to detect behaviorally relevant visual changes. In addition, we found that SC inhibition also caused deficits in visual target selection. Thus, our findings highlight the importance of the SC for visual perceptual choice behavior in the mouse.

Can short-term memory be trained?

Is the capacity of short-term memory fixed, or does it improve with practice? It is already known that training on complex working memory tasks is more likely to transfer to untrained tasks with similar properties, but this approach has not been extended to the more basic short-term memory system responsible for verbal serial recall. Here we investigated this with adaptive training algorithms widely applied in working memory training. Serial recall of visually presented digits was found to improve over the course of 20 training sessions, but this improvement did not extend to recall of either spoken digits or visually presented letters. In contrast, training on a nonserial visual short-term memory color change detection task did transfer to a line orientation change detection task. We suggest that training only generates substantial transfer when the unfamiliar demands of the training activities require the development of novel routines that can then be applied to untrained versions of the same paradigm (Gathercole, Dunning, Holmes, & Norris, 2019). In contrast, serial recall of digits is fully supported by the existing verbal short-term memory system and does not require the development of new routines.

Working memory contents outside the focus of attention are represented by different neural populations not in an activity-silent state

Some contents held in visual working memory are thought to be retained in a prioritized state typically referred to as the 'focus of attention', while other items are considered to be 'unattended', or 'accessory'. Attempts to identify and read out such unattended memory representations in the human brain using fMRI have so far only resulted in null findings, leading some to postulate that unattended items are retained in an 'activity-silent state', for example by synaptic mechanisms. Here, we revisited this important question to test an alternative explanation for previous null results: Attended and unattended items are retained by separate patterns of neural activity which might even be localized in different brain areas. In the experiment, participants memorized the orientation of two Gabor patches in an MRI scanner. A first cue, indicated that one of the two stimuli should be used for a first orientation change detection task making it the attended memory content for a first delay. After this first task, a second cue could select the other orientation for a second task, ensuring that participants had to maintain both orientations during the first delay. We analyzed fMRI data from this maintenance interval using cvMANOVA MVPA and a large set of regions of interest to independently identify information about the attended and the unattended item. Information about the attended orientation stored in working memory was found predominantly in V1, as well as inferior and superior parietal areas. Importantly, the information about the not prioritized or unattended working memory orientation was represented in the intraparietal sulcus within the same maintenance interval, where no information was found for the attended item. Finding separate representations of currently relevant and irrelevant working memories demonstrates separate activity-based storage mechanisms for attended and unattended items.

Discrete item-based and continuous configural representations in visual short-term memory

ABSTRACTBoth discrete item-based and global configural information can be stored in visual short-term memory (VSTM). To characterize their contribution, the present study developed a dual-trace signal detection (DTSD) model consisting of a high threshold (HT) component for discrete item information and a continuous signal detection theory (SDT) component for configural information. We used an orientation change-detection task in which observers attempted to retain several orientations over a 1-s retention interval and then reported whether a cued item in the test array had the old or new orientation on a 6-point confidence scale. The resulting Receiver Operating Characteristics (ROC) curves were fit with the DTSD model, producing estimates of the two memory representations. In a series of experiments, we found that manipulations of configural encoding selectively affected the SDT component whereas the manipulation of item information selectively affected the HT component. Together these findings indicate that VSTM maintains a few discrete representations and continuous representation of configural information.

Automatic detection of orientation changes of faces versus non-face objects: A visual MMN study

To investigate the automatic change detection of faces versus non-face objects, the visual mismatch negativity (vMMN) elicited by deviant orientation (90° versus 0°) for faces and houses, respectively, was recorded using the deviant-standard-reversed paradigm. The present face stimuli elicited larger N170 than did houses, regardless of the orientation. A larger and delayed N170 for deviant rotated faces was elicited than that for standard rotated faces, whereas the N170 did not differ between deviant and standard rotated houses. The rotated faces elicited increased vMMN amplitude and decreased vMMN latency than did the rotated houses. The face-MMN with a right occipito-temporal scalp distribution was larger for the rotated than upright conditions but the orientation did not modulate the amplitudes of house MMN. These data provided electrophysiological evidence for larger sensitivity for orientation changes of faces than those of objects even in the absence of attention, due to the disruption of configural processing caused by face rotation.

TMS of the anterior intraparietal area selectively modulates orientation change detection during action preparation

Perception of relevant visual object features can be modulated by the preparation of an action toward it ("action-modulated perception"). For instance, the perception of the orientation of a book can be enhanced when preparing to grasp it (but not when pointing to it). However, the underlying neuronal mechanisms are poorly understood. We argue that brain areas controlling arm movements are involved in establishing this effect through top-down feedback to early visual areas, similar to the neuronal mechanisms linking visual attention and eye movements. To investigate this involvement, we applied transcranial magnetic stimulation to a grasping motor area, the left anterior intraparietal sulcus (aIPS), during grasping or pointing preparation. Concurrently, an orientation change detection task was performed. As a control area, the vertex was stimulated. We found that stimulation of aIPS selectively modulates orientation sensitivity during action preparation compared with control stimulation (vertex), negating the increased orientation sensitivity with grasping preparation over pointing preparation. We argue that aIPS is a critical part of the mechanism underlying perceptual modulations during action preparation. The present results and recent literature suggest that this action-modulated perception for hand movements is implemented through a cortical feedback connection between aIPS and early visual areas.

Probabilistic Computation in Human Perception under Variability in Encoding Precision

A key function of the brain is to interpret noisy sensory information. To do so optimally, observers must, in many tasks, take into account knowledge of the precision with which stimuli are encoded. In an orientation change detection task, we find that encoding precision does not only depend on an experimentally controlled reliability parameter (shape), but also exhibits additional variability. In spite of variability in precision, human subjects seem to take into account precision near-optimally on a trial-to-trial and item-to-item basis. Our results offer a new conceptualization of the encoding of sensory information and highlight the brain’s remarkable ability to incorporate knowledge of uncertainty during complex perceptual decision-making.

The influence of location and visual features on visual object memory

In five experiments, we examined the influence of contextual objects' location and visual features on visual memory. Participants' visual memory was tested with a change detection task in which they had to judge whether the orientation (Experiments 1A, 1B, and 2) or color (Experiments 3A and 3B) of a target object was the same. Furthermore, contextual objects' locations and visual features were manipulated in the test image. The results showed that change detection performance was better when contextual objects' locations remained the same from study to test, demonstrating that the original spatial configuration is important for subsequent visual memory retrieval. The results further showed that changes to contextual objects' orientation, but not color, reduced orientation change detection performance; and changes to contextual objects' color, but not orientation, impaired color change detection performance. Therefore, contextual objects' visual features are capable of affecting visual memory. However, selective attention plays an influential role in modulating such effects.

Orientation change detection and orientation pooling in space and time performed by two subpopulations of neurons in V2

Neurons in V1 mainly extract oriented luminance boundaries, while neurons in V2 detect more complex boundaries, including texture boundaries. Here we investigate the processing of orientation signals in V1 and V2, and find two distinct subpopulations of neurons in V2 based on their dynamics. We recorded responses from single neurons in V1 and V2 of anesthetized monkeys. Stimuli consisted of a 4x5 or 6x6 grid of adjacent rectangular regions, covering the non-classical receptive field. Each region contained sinusoidal gratings with either the preferred orientation or the non-preferred orthogonal orientation controlled by m-sequences (frame rate 20 ms or 40 ms). V1 neurons have monophasic responses to the orientation signal in individual regions, and their timing is consistent across the population. In contrast, V2 neurons have two distinct patterns of responses: some are biphasic, with an initial peak width narrower than the V1 responses (‘transient V2 neurons’); others are monophasic, with a broader peak than the V1 responses (‘sustained V2 neurons’). The biphasic response pattern indicates dynamic orientation tuning and predicts that the optimal stimulus within a patch is the non-preferred orientation followed by the preferred orientation. Responses to combinations of orientations reveal additional distinctions between V1 and the two V2 subpopulations. Neurons in V1 have nonlinear interactions consistent with cross-orientation suppression. Transient V2 neurons exhibit the opposite: larger responses to orientation discontinuities than to continuous orientation. Sustained V2 neurons show no measurable nonlinear spatial interaction. This study shows, firstly, how non-linear as well as linear responses of V2 neurons differ from V1 responses. Secondly, we identified two different classes of orientation selective V2 neurons. The transient V2 neurons differentiate the V1 input in space and time and therefore respond well to changes in orientation. Sustained V2 neurons pool the V1 input and respond better to constant orientation signals.

Three-month-olds’ sensitivity to orientation cues in the three-dimensional depth plane

Three-month-olds are sensitive to orientation changes of line drawings when they have a three-dimensional (3-D) interpretation and when the changes are defined by both 3-D depth and two-dimensional (2-D) picture plane cues [Bhatt, R. S., & Bertin, E. (2001). Pictorial cues and three-dimensional information processing in early infancy. Journal of Experimental Child Psychology, 80, 315–332]. In the current study, we examined whether 3-month-olds are sensitive to pictorial line junction cues that signal orientation changes solely in the 3-D depth plane. The results revealed that infants discriminated a misoriented elongated cube in an array when the stimuli contained both shading and lines (Experiment 2) but not when only lines depicted the elongated cubes (Experiment 1). Testing with comparable 2-D images revealed that, even in the presence of shading information, detection of orientation changes is specific to images that have a 3-D interpretation. Together, the results suggest that 3-month-olds are sensitive to pictorial line junction cues that signal orientation changes in the 3-D depth plane to adults provided that shading information is available and the images have a 3-D interpretation.