Horizontal Saccadic Eye Movements Research Articles

Saccade Induced Retrieval Enhancement, Handedness & the Retrieval of Central & Peripheral Details in Eyewitness Memory

Two experiments are presented that investigated the effects of horizontal saccadic eye movements and handedness on eyewitness memory for central and peripheral information. In both experiments, participants viewed a short video depicting a bank robbery and episodic memory was tested after a short delay. Experiment 1 used recognition memory and found an interaction between eye movement, handedness and type of information recalled. This indicated that eye movements enhanced memory to a greater extent for peripheral information for individuals classified as consistently handed. Experiment 2 used free-recall and found eye movement enhancement effects of similar magnitude for central and peripheral items. A similar pattern of eye movement effects was observed for both consistent and inconsistent-handed individuals. Inconsistent handers also had superior memory overall. The results are discussed in terms of theoretical accounts of eye movement effects and implications for the enhancement of eyewitness memory.

Diabetic older women without peripheral neuropathy amplify body sway but are capable of improving postural stability during a saccadic gaze task

BackgroundDiabetic older people tend to present deteriorated performance in balance and locomotion activities, even those without peripheral neuropathy. There is evidence that saccadic eye movements are used to reduce body sway in young and older healthy adults, but it has not been shown that diabetic older people preserve this visuomotor adaptation capacity. Research questionAre diabetic older women without peripheral neuropathy capable of improving postural stability during a saccadic gaze task? MethodsSeventeen type 2 diabetic older women (68.2 ± 10.7 years old) and seventeen healthy women, age-matched controls (66.0 ± 8.4 years old) voluntarily participated in the study. All participants were instructed to stand upright, barefoot, as stable as possible, for 30 s. Participants maintained their feet parallel to each other, at standard and narrow bases of support, while either fixating on a stationary target (fixation condition) or performing horizontal saccadic eye movements to follow a target (eccentricity of 11° of visual angle), which continuously disappeared and reappeared immediately on the opposite side (saccade 0.5 Hz and saccade 1.1 Hz conditions). ResultsResults indicated that the diabetic group clearly had deteriorated postural control, as shown by increased values of mean sway amplitude and mean sway velocity. However, diabetic and control groups were similarly capable of using saccadic eye movements to improve their postural stability, reducing their sway velocity compared to a gaze fixation condition. SignificanceDiabetes per se (without peripheral neuropathy) amplifies postural sway of older women as compared to their healthy age-matched controls. However, diabetic older women without peripheral neuropathy are capable of improving postural stability during a saccadic gaze task.

Changes in saccadic eye movement and smooth pursuit gain in patients with acquired comitant esotropia after strabismus surgery.

This study investigates the change in horizontal saccadic eye movement and smooth pursuit in patients with acquired comitant esotropia (ACE), before and after strabismus surgery. The horizontal saccades and pursuit in 11 patients with ACE were recorded using a video eye-tracker under binocular viewing before and after strabismus surgery. Participants were instructed to fixate on the new target as rapidly as possible when it randomly appeared at either 18.3° rightward or 18.3° leftward. For smooth pursuit, participants were asked to track, as accurately as possible, a step-ramp target moving at ±6.1°/s. The asymmetry of adduction-abduction and the binocular coordination in gains of saccade and pursuit were compared between the pre- and post-surgical data. The asymmetry of adduction-abduction saccade gain in each eye after surgery tended to be smaller than that before surgery. The binocular coordination of saccade showed significant improvement after surgery in only the non-dominant eye direction. Adduction-abduction asymmetry in the smooth pursuit gain in each eye after surgery tended to be smaller than before surgery. After surgery, the binocular coordination of pursuit was improved significantly in both directions. In patients with ACE, binocular coordination of saccade and smooth pursuit was poor. Binocular coordination of saccade and pursuit seems to be improved due to the improvement in ocular deviation angle and binocular visual function after surgery.

Progressive Supranuclear Palsy

Progressive supranuclear palsy (PSP) has been reported as a disorder mainly characterized by a tendency to fall, vertical supranuclear gaze palsy, and constriction of the body axis, akinesia, and cognitive impairment. Patients presenting with these typical clinical features are diagnosed as having the PSP-Richardson syndrome (PSP-RS). Electronystagmography (ENG) is useful for the detection of ocular motility disorder, which is the main feature of PSP. In cases of PSP, ocular motility disorder in the vertical direction occurs from the initial stage of the disease, and is characterized by prolonged latency and reduced velocity of the saccadic eye movement in the vertical direction. Horizontal saccadic eye movement disorder also occurs after the intermediate stage. Square wave jerks (SWJ) are often recognized from the initial stage of the disease. In terms of nystagmus, the quick phase is impaired due to impaired saccadic eye movements, and impairment of optokinetic nystagmus also starts from the quick phase movements. Pursuit (smooth) eye movement may also be impaired as the disease progresses. On the other hand, the vestibulo-ocular reflex is maintained even after disease progression to a late stage.

Visual and cognitive profiles in children with and without cerebral visual impairment

Reliable differentiation of visual-perceptual difficulties in children with and without cerebral visual impairment (CVI) can often pose a diagnostic challenge. We, therefore, assessed the visual-perceptual profile in 94 children with and 77 children without suspected CVI between the ages of 8 and 17 years in a non-clinical setting, using a screening questionnaire and standardized visual-perceptual tests. Children with suspected CVI reported more frequently greater visual difficulties, had lower visual acuity, and were significantly impaired in visual search tests, in visual form and object perception, in visual space perception, and in visual text processing. There were no significant differences between groups in stereopsis, fixation stability, motility, horizontal saccadic eye movements, and convergence and accommodation. Cognitive performance in auditory attention and verbal short-term and working memory was similar in both groups. Our results indicate that the use of an appropriate questionnaire and specific visual-perceptual tests enables valid diagnostic detection of CVI. The additional use of cognitive tests also allows differentiation between primary and secondary impairments in visual perception.

Neurophysiology, pathology and models of rapid eye movements.

This chapter discusses the premotor neural mechanisms that control horizontal saccadic eye movements. Oculomotoneurons carry a pulse-step signal that underlies the pulse-step force driving the overdamped plant. The pulse and step are both generated by a common signal, arising from medium-lead burst neurons in the pons. Their burst signal encodes saccadic eye velocity, while the number of spikes in the burst relates to the saccade amplitude. The step component, which encodes the eye position, is obtained by neural integration of the burst. Several oculomotor neural disorders can be explained by impairments in the binocular push-pull organization of this pulse-step mechanism. Plasticity of the pulse-step control, e.g., in response to muscle weakening, is mediated by cerebellar vermis and flocculus. Saccadic offset may be controlled, either by active braking, or by an exponential slide signal. The neurophysiology is summarized by a quantitative model, in which the firing rate of burst neurons is controlled by a dynamic negative feedback loop that carries the instantaneous eye position signal from the neural integrator. This signal is compared with a desired eye-position command in the head from higher centers, and the resulting dynamic motor error drives the high-gain burst cells. Instability of the system is prevented by the mutual inhibitory interaction between burst cells and omnipause neurons. The model explains many features of normal saccades, but also accounts for pathologies and abnormalities like dynamic overshoots and saccade oscillations.

Trunk and head displacements stabilized to perform both horizontal and vertical saccadic eye movements.

Vision is crucial for humans to interact with their surrounding environment, and postural sway is reduced to allow short eye movements. However, the extent of subtle changes in postural control for horizontal and vertical eye movements remains unclear. The goal of this study was to investigate the effects of vertical and horizontal eye movements on head and trunk control in young adults. Fifteen healthy adults (23.4 ± 4.7years) stood upright in three conditions for 60s: fixation, horizontal, and vertical guided eye movements. In fixation, participants had to fixate on a stationary target. In both the horizontal and vertical eye movements, the target was presented with a frequency of 0.5Hz and a visual angle of 11°. Eye displacement was monitored using a SMI eye tracker (ETG2.0) and trunk and head sway were monitored using infrared markers (Optotrak 3020, NDI). The mean sway amplitude was lower in both directions for eye movements and lowest in the vertical direction compared to the fixation condition. The sway area was also lower in vertical eye movement than in the fixation condition. We also found that the sway reduction was greater at head than at trunk level. The median frequency sway in the anterior-posterior direction was higher in both eye movements than in fixation. Based upon these results, we suggest that to perform short eye movements, postural sway is more strongly controlled at the head level than at the trunk and in vertical eye movements than in horizontal movements.

Electrovestibulography (EVestG) application for measuring vestibular response to horizontal pursuit and saccadic eye movements

Vestibular effects linked to eye movements have been extensively investigated, however, the effect of eye movements on the vestibular is relatively unknown. In this study, vestibular responses to horizontal pursuit and saccadic eye movements were examined in healthy individuals. Visual stimuli were presented to nineteen participants (27.7 ± 5.74 (SD) years, 11 female) using a virtual reality headset whilst the vestibular responses were simultaneously recorded using Electrovestibulography (EVestG). The average field potentials (FP) of three segments 1) prior to (Pre-Background), 2) during (Movement), and 3) after ceasing the visual stimulus (Post-Background) were extracted and the action potential (AP) area used as one feature. Both pursuit and saccadic eye movements resulted in a smaller average AP area during the Movement compared to Pre-Background (P = 0.002). Pursuit and saccadic eye movements also resulted in significantly longer time intervals between the low frequency (approximately 10 Hz) modulations of FPs detected during Movement compared to the Pre-Background (P ≤ 0.001). Moreover, a comparison between rightward and leftward saccades indicated no significant difference between the two directions for the FP and time interval features (P > 0.37). These findings suggest that pursuit and saccade eye movements inhibit the activity of both the central (postulated efferent pathways) and peripheral (afferent) vestibular system. We hypothesize that the purpose of this vestibular inhibition is to limit the vestibulo-ocular reflex and optokinetic response. Additionally, the insensitivity of the vestibular system to the saccade directions with a stationary head provides anecdotal evidence on the bilateral efferent projections to the vestibular afferent and hair cells.

Low-Level Visual Information Is Maintained across Saccades, Allowing for a Postsaccadic Handoff between Visual Areas.

Experience seems continuous and detailed despite saccadic eye movements changing retinal input several times per second. There is debate whether neural signals related to updating across saccades contain information about stimulus features, or only location pointers without visual details. We investigated the time course of low-level visual information processing across saccades by decoding the spatial frequency of a stationary stimulus that changed from one visual hemifield to the other because of a horizontal saccadic eye movement. We recorded magnetoencephalography while human subjects (both sexes) monitored the orientation of a grating stimulus, making spatial frequency task irrelevant. Separate trials, in which subjects maintained fixation, were used to train a classifier, whose performance was then tested on saccade trials. Decoding performance showed that spatial frequency information of the presaccadic stimulus remained present for ∼200 ms after the saccade, transcending retinotopic specificity. Postsaccadic information ramped up rapidly after saccade offset. There was an overlap of over 100 ms during which decoding was significant from both presaccadic and postsaccadic processing areas. This suggests that the apparent richness of perception across saccades may be supported by the continuous availability of low-level information with a “soft handoff” of information during the initial processing sweep of the new fixation.SIGNIFICANCE STATEMENT Saccades create frequent discontinuities in visual input, yet perception appears stable and continuous. How is this discontinuous input processed resulting in visual stability? Previous studies have focused on presaccadic remapping. Here we examined the time course of processing of low-level visual information (spatial frequency) across saccades with magnetoencephalography. The results suggest that spatial frequency information is not predictively remapped but also is not discarded. Instead, they suggest a soft handoff over time between different visual areas, making this information continuously available across the saccade. Information about the presaccadic stimulus remains available, while the information about the postsaccadic stimulus has also become available. The simultaneous availability of both the presaccadic and postsaccadic information could enable rich and continuous perception across saccades.

A comprehensive monocentric ophthalmic study with Gaucher disease type 3 patients: vitreoretinal lesions, retinal atrophy and characterization of abnormal saccades

SummaryBackgroundThe differentiation between Gaucher disease type 3 (GD3) and type 1 is challenging because pathognomonic neurologic symptoms may be subtle and develop at late stages. The ophthalmologist plays a crucial role in identifying the typical impairment of horizontal saccadic eye movements, followed by vertical ones. Little is known about further ocular involvement. The aim of this monocentric cohort study is to comprehensively describe the ophthalmological features of Gaucher disease type 3. We suggest recommendations for a set of useful ophthalmologic investigations for diagnosis and follow up and for saccadometry parameters enabling a correlation to disease severity.MethodsSixteen patients with biochemically and genetically diagnosed GD3 completed ophthalmologic examination including optical coherence tomography (OCT), clinical oculomotor assessment and saccadometry by infrared based video-oculography. Saccadic peak velocity, gain and latency were compared to 100 healthy controls, using parametric tests. Correlations between saccadic assessment and clinical parameters were calculated.ResultsPeripapillary subretinal drusen-like deposits with retinal atrophy (2/16), preretinal opacities of the vitreous (4/16) and increased retinal vessel tortuosity (3/16) were found. Oculomotor pathology with clinically slowed saccades was more frequent horizontally (15/16) than vertically (12/16). Saccadometry revealed slowed peak velocity compared to 100 controls (most evident horizontally and downwards). Saccades were delayed and hypometric. Best correlating with SARA (scale for the assessment and rating of ataxia), disease duration, mSST (modified Severity Scoring Tool) and reduced IQ was peak velocity (both up- and downwards). Motility restriction occurred in 8/16 patients affecting horizontal eye movements, while vertical motility restriction was seen less frequently. Impaired abduction presented with esophoria or esotropia, the latter in combination with reduced stereopsis.ConclusionsVitreoretinal lesions may occur in 25% of Gaucher type 3 patients, while we additionally observed subretinal lesions with retinal atrophy in advanced disease stages. Vertical saccadic peak velocity seems the most promising “biomarker” for neuropathic manifestation for future longitudinal studies, as it correlates best with other neurologic symptoms. Apart from the well documented abduction deficit in Gaucher type 3 we were able to demonstrate motility impairment in all directions of gaze.

Low-Level Visual Information is Maintained Across Saccades by a 'Soft Hand-Off' between Visual Processing Areas

Subjective visual experience of a rich, detailed visual scene seems continuous despite us making several saccadic eye movements every second which radically change retinal input. Here, we investigated the time course of low-level visual information processing in the brain by decoding spatial frequency of an attended, stationary stimulus that changed from one visual hemifield to another due to a horizontal saccadic eye movement. Magneto-encephalography (MEG) was recorded while human participants made a large horizontal saccade and monitored the orientation of a grating stimulus, making spatial frequency task-irrelevant. Separate trials, in which participants maintained fixation, were used to train a classifier that was tested during saccade trials. Decoding performance showed that information about spatial frequency was present in the original retinotopic areas before, during and up to around 200 ms after the saccade. Post-saccadic information rapidly ramped up within a few tens of milliseconds, allowing for rapid decoding from the new retinotopic areas. There was an overlap of over 100 ms during which decoding was significant from both pre- and post-saccadic processing areas. These results suggest that the apparent richness of perception across saccades may be supported by the continuous availability of the low-level spatial frequency information that supports gist, object and ensemble perception, with a “soft hand-off” of this information during the initial visual processing sweep of the new fixation. Such a mechanism does not require remapping of low-level visual information before the saccade.

Central mesencephalic reticular formation control of the near response: lens accommodation circuits.

To view a nearby target, the three components of the near response are brought into play: 1) the eyes are converged through contraction of the medial rectus muscles to direct both foveae at the target, 2) the ciliary muscle contracts to allow the lens to thicken, increasing its refractive power to focus the near target on the retina, and 3) the pupil constricts to increase depth of field. In this study, we utilized retrograde transsynaptic transport of the N2c strain of rabies virus injected into the ciliary body of one eye of macaque monkeys to identify premotor neurons that control lens accommodation. We previously used this approach to label a premotor population located in the supraoculomotor area. In the present report, we describe a set of neurons located bilaterally in the central mesencephalic reticular formation that are labeled in the same time frame as the supraoculomotor area population, indicating their premotor character. The labeled premotor neurons are mostly multipolar cells, with long, very sparsely branched dendrites. They form a band that stretches across the core of the midbrain reticular formation. This population appears to be continuous with the premotor near-response neurons located in the supraoculomotor area at the level of the caudal central subdivision of the oculomotor nucleus. The central mesencephalic reticular formation has previously been associated with horizontal saccadic eye movements, so these premotor cells might be involved in controlling lens accommodation during disjunctive saccades. Alternatively, they may represent a population that controls vergence velocity. NEW & NOTEWORTHY This report uses transsynaptic transport of rabies virus to provide new evidence that the central mesencephalic reticular formation (cMRF) contains premotor neurons controlling lens accommodation. When combined with other recent reports that the cMRF also contains premotor neurons supplying medial rectus motoneurons, these results indicate that this portion of the reticular formation plays an important role in directing the near response and disjunctive saccades when viewers look between targets located at different distances.

Oculomotor Function in Individuals With Rett Syndrome

BackgroundIndividuals with Rett syndrome (RTT) are notoriously reliant on the use of eye gaze as a primary means of communication. Underlying an ability to communicate successfully via eye gaze is a complex matrix of requirements, with an intact oculomotor system being just one element. To date, the underlying neural and motor pathways associated with eye gaze are relatively under-researched in RTT. PurposeThis study was undertaken to plug this gap in knowledge and to further the understanding of RTT in one specific area of development and function, namely oculomotor function. Material and MethodsThe eye movements of 18 girls and young women with RTT were assessed by electronystagmography (ENG). This tested their horizontal saccadic and smooth pursuit eye movements as well as optokinetic nystagmus and vestibulo-ocular reflex. Their results were compared with normative data collected from 16 typically developing children and teenagers. ResultsOverall, the individuals with RTT demonstrated a range of eye movements on a par with their typically developing peers. However, there were a number of difficulties in executing the ENG testing with the RTT cohort which made quantitative analysis tricky, such as reduced motivation and attention to test materials and low-quality electrode signals. ConclusionsThis study suggests that individuals with RTT have an intact oculomotor system. However, modifications should be made to the ENG assessment procedure to combat problems in testing and add strength to the results. Further investigation into these testing difficulties is warranted in order to inform such modifications.

EVALUATION OF VERTICAL AND HORIZONTAL SACCADES USING THE DEVELOPMENTAL EYE MOVEMENT TEST COMPARED TO THE KING-DEVICK TEST

Oculomotor function is impaired when an individual has a concussion and as such, it is important to identify tests that are able to assess oculomotor impairment. The King-Devick (K-D) test assesses horizontal saccadic eye movement and attention. The Developmental Eye Movement (DEM) test is designed to identify oculomotor dysfunction in children. It measures both horizontal and vertical saccades. The K-D test shows promise as a concussion-screening tool and part of a multifactorial assessment. The DEM has not been tested as a concussion assessment tool, but the neuroanatomical control of horizontal and vertical saccades originates from different areas of the brain, so one might expect to see differences in performance on the K-D and DEM tests when administered to concussed patients. First, it is important to determine if performance on the DEM and K-D tests, particularly with respect to the measurement of vertical and horizontal saccades, is similar in a healthy population.Hypothesis/Purpose: The primary purpose was to evaluate the relationship between horizontal and vertical saccade tests over repeated trials in normal, healthy subjects. A secondary purpose of this study was to determine the number of trials needed to reach a performance plateau for both the DEM and K-D tests.Study Design: This study used a prospective cohort research design. Forty-two healthy non-concussed participants (22 males, 20 females; mean age, 24.2 ± 2.92 years) completed six repeated trials of both the DEM, and then six trials of the K-D test in a single testing session. Trials within each test were performed in random order and participants were offered short rest breaks as needed between test administrations. Results indicated strong correlations, r=.67, or greater, between measurements of horizontal and vertical saccades. Performance plateaued on the K-D at trial three and on the DEM at trial two for both horizontal and vertical saccades. It appears that the DEM and K-D tests measure similar constructs in healthy individuals and that no additional information is provided by assessment of vertical saccades. Additional studies are required to investigate the usefulness of the DEM in concussed individuals. 3: Laboratory study with repeated measures.

Eye movement abnormalities in AQP4-IgG positive neuromyelitis optica spectrum disorder

Background and purposeNeuromyelitis optica spectrum disorder (NMOSD) has been recognized as a disease characterized by severe visual afferent impairment. Abnormal eye movements, as the other important neuro-ophthalmic manifestation of NMOSD, were commonly overlooked. The aim of our study was to describe the ocular motor manifestations of AQP4-IgG positive NMOSD patients, and explore the value of eye movement abnormalities in the evaluation of the disabled disease. MethodsSystemic clinical bedside ocular motor examinations and quantitative horizontal saccadic eye movement assessments were performed in 90 patients with AQP4-IgG positive NMOSD. General disability was evaluated by expanded disability status scale (EDSS). Vision-specific functional status was evaluated by the National Eye Institute-Visual Function Questionnaire (NEI-VFQ 25) and the 10-item neuro-ophthalmic supplement. Brain magnetic resonance imaging (MRI) was acquired in all patients. ResultsIn clinical examination, eye movement abnormalities were found in 38% of NMOSD patients. Abnormalities in the quantitative saccadic test were found in 67% of NMOSD patients, including 48% of patients with clinically normal eye movements. EDSS scores in patients with clinical eye movement abnormality were significantly higher (P<0.001) than those with a normal examination. The 10-item neuro-ophthalmic supplement score was significantly associated with quantitative saccadic eye movement abnormalities (P=0.031). ConclusionsEye movement abnormalities were common in AQP4-IgG positive NMOSD patients, and were associated with general disability and specific visual handicap. The systemic clinical eye movement examination combined with the quantitative saccade test was easy to perform, and could provide additional useful information in evaluating NMOSD.

A Neural Control Model for Horizontal Visual, Auditory and Auditory-Visual Bisensory Stimuli Elicited Saccades

To provide a comprehensive investigation of goal-oriented saccades, experiments are designed to trigger fast eye movements by different types of targets, including visual, auditory, and auditory-visual bisensory stimuli. Human saccades are recorded using a high speed eye tracking system. Data is analyzed to produce parameter estimates using system identification technique for a 3rd-order linear horizontal saccadic eye movement model. Saccade characteristics are explored and compared. The auditory-visual stimuli provide the greatest saccade accuracy. Auditory saccades show lower peak velocity and longer duration. Saccade latent period is relatively independent of saccade amplitude, but there is a significant reduction in the bisensory saccades. Neural inputs of saccades are estimated and analyzed as well. Auditory saccades exhibit lower agonist pulse magnitude and longer agonist pulse duration. Antagonist onset delay is longer in auditory saccades. Post saccade phenomena are caused by the post-inhibitory rebound burst of the antagonist motoneurons. There is a higher incidence of dynamic overshoot in auditory saccades than visual saccades, with more in the abducting direction than the adducting direction.

Horizontal Saccadic Eye Movements to Visual and Auditory-Visual Double-Step Stimuli: Saccade Characteristics and Neural Input Estimations

Goal-oriented human saccades were recorded under double-step paradigm. The stimuli consisted of either visual or auditory-visual bi-sensory targets. Eye movement data were analyzed based on a 3rd-order linear horizontal saccadic eye movement model, where the inputs to the muscle were agonist and antagonist active-state tensions that were described by pulse-slide-step waveforms with a post inhibitory rebound burst (PIRB) based on a timeoptimal controller. Parameter estimations were calculated using the system identification technique for saccade parameters and neural inputs. Saccade amplitude transition function (ATF) and response latency indicated the saccade programming mechanism. The responses were affected by when the second peripheral target was presented. The neural input estimations supported the responsive neuron populations in the superior colliculus under different stimulus conditions, and indicated the double-step visual or auditory-visual stimulus may affect the synchrony of neuron firing. The study described here expanded our previous work and further supported the muscle model as well as the theory of the time-optimal saccade controller under physiological constraints.

Visually Guided Horizontal Saccades under the Double-Step Paradigm

Visually goal-oriented saccades were recorded under the double-step paradigm. Data were analyzed to produce parameter estimates using the system identification technique for a 3rd-order linear horizontal saccadic eye movement model. Statistical analysis of a large human saccade data set provided reliable conclusions of the response properties. Saccade amplitude, latency and inter-saccade interval were discussed with time delay, indicating the parallel programming mechanism, which two saccades to different targets could be programmed simultaneously. The results of neural input estimations suggested that the double-step visual targets may affect the synchronous firing of the saccade responsible neurons in the superior colliculus.

The effect of horizontal eye movements on free recall: a preregistered adversarial collaboration.

A growing body of research has suggested that horizontal saccadic eye movements facilitate the retrieval of episodic memories in free recall and recognition memory tasks. Nevertheless, a minority of studies have failed to replicate this effect. This article attempts to resolve the inconsistent results by introducing a novel variant of proponent-skeptic collaboration. The proposed approach combines the features of adversarial collaboration and purely confirmatory preregistered research. Prior to data collection, the adversaries reached consensus on an optimal research design, formulated their expectations, and agreed to submit the findings to an academic journal regardless of the outcome. To increase transparency and secure the purely confirmatory nature of the investigation, the 2 parties set up a publicly available adversarial collaboration agreement that detailed the proposed design and all foreseeable aspects of the data analysis. As anticipated by the skeptics, a series of Bayesian hypothesis tests indicated that horizontal eye movements did not improve free recall performance. The skeptics suggested that the nonreplication may partly reflect the use of suboptimal and questionable research practices in earlier eye movement studies. The proponents countered this suggestion and used a p curve analysis to argue that the effect of horizontal eye movements on explicit memory did not merely reflect selective reporting.

Hemispheric bases for emotion and memory.

Hemispheric bases for emotion and memory.