Pupillometry system for use in social psychology

It is now relatively easy to implement pupillometry in social psychological research. We describe a system in which a Macintosh computer presents visual and auditory stimuli to subjects while monitoring an infrared pupillometer. The computer records information on subject, task, and pupil diameter into a data file for input into standard statistical analysis programs. Pupil diameter is measured continuously while subjects respond to stimuli that last for several seconds or minutes. A demonstration experiment verifies the usefulness of the system. The ability of the Macintosh computer to easily handle visual and auditory stimuli and to record responses lasting a considerable length of time makes the system well suited for studying pupil responses to complex social stimuli. This system is also well suited for the researcher initiating a research program using pupillometry. Ease of operation makes using a large number of subjects feasible.     

The effects of sound on pupil size and the pupil light reflex

The effects of auditory stimulation on pupil size and the pupil light reflex were investigated in 33 male volunteers. A 95dB tone caused pupillary dilation and a reduction in the amplitude of the light reflex. Although the light reflex amplitude was positively correlated with pupil size in the resting state the effects of noise on the two measures were independent since the pupillary dilation response showed a marked habituation after two presentations of the tone whereas the effect on the light reflex remained the same. People showing high impulsivity scores on the EPQ tended to have smaller pupils (i.e. low arousal). There was also a relationship between impulsivity and light reflex amplitude, but this was probably a secondary consequence of the relationship between the latter measure and pupil size in the resting state.     

Pupillary correlates of covert shifts of attention during working memory maintenance

The pupillary light reflex (PLR) was used to track covert shifts of attention to items maintained in visual working memory (VWM). In three experiments, participants performed a change detection task in which rectangles appeared on either side of fixation and at test participants indicated if the cued rectangle changed its orientation. Prior to presentation or during the delay, participants were cued to the light or dark side of the screen. When cued to the light side, the pupil constricted, and when cued to the dark side, the pupil dilated, suggesting that the PLR tracked covert shifts of attention. Similar covert shifts of attention were seen when the target stimuli remained onscreen and during a blank delay period, suggesting similar effects for attention to perceptual stimuli and attention to stimuli maintained in VWM. Furthermore, similar effects were demonstrated when participants were pre-cued or retro-cued to the prioritized location, suggesting that shifts of covert attention can occur both before and after target presentation. These results are consistent with prior research, suggesting an important role of covert shifts of attention during VWM maintenance and that the PLR can be used to track these covert shifts of attention.     

Glance analysis of driver eye movements to evaluate distraction

With the increasing use of in-vehicle devices in cars, an understanding of the safety implications of secondary tasks has become crucial. It is now possible to study the effects of many in-vehicle devices and tasks on driving by using head-mounted eye-tracking devices (HEDs) to collect eye positions and pupil diameters, which have been considered indicators of attentional focus. The collection of eye-position and pupil-diameter data of automobile drivers under on-road conditions and while completing various secondary tasks is described in this paper. Drivers were asked to drive on a preselected two-lane road for a total distance of 22 miles while gaze data were recorded using a HED. Longer off-road fixation durations were observed in radio-tuning and rearview mirror checking tasks, but not in the odometer checking task. In addition, the standard deviations of fixation displacements during a cognitive task involving the computation of a date for a meeting were shorter than those observed during normal driving.     

The relationship between baseline pupil size and intelligence

Pupil dilations of the eye are known to correspond to central cognitive processes. However, the relationship between pupil size and individual differences in cognitive ability is not as well studied. A peculiar finding that has cropped up in this research is that those high on cognitive ability have a larger pupil size, even during a passive baseline condition. Yet these findings were incidental and lacked a clear explanation. Therefore, in the present series of studies we systematically investigated whether pupil size during a passive baseline is associated with individual differences in working memory capacity and fluid intelligence. Across three studies we consistently found that baseline pupil size is, in fact, related to cognitive ability. We showed that this relationship could not be explained by differences in mental effort, and that the effect of working memory capacity and fluid intelligence on pupil size persisted even after 23 sessions and taking into account the effect of novelty or familiarity with the environment. We also accounted for potential confounding variables such as; age, ethnicity, and drug substances. Lastly, we found that it is fluid intelligence, more so than working memory capacity, which is related to baseline pupil size. In order to provide an explanation and suggestions for future research, we also consider our findings in the context of the underlying neural mechanisms involved.     

Eye Metrics: An Alternative Vigilance Detector for Military Operators

Military operators in various environments such as cyber, remotely piloted aircraft, and image analysis are required to use sustained attention or vigilance for long periods. During this time they encounter lapses in attention attributable to the monotonous nature of their tasks. Mistakes during these tasks can have serious consequences. The purpose of this study was to investigate the use of an eye-tracker to detect changes in vigilance performance during a simulated cyber operator task. Twenty participants performed 4 sessions of a 40-min vigilance task while wearing an eye-tracker. Blink frequency, blink duration, PERCLOS (percentage of eye closure), pupil diameter, pupil eccentricity, pupil velocity, and signal detection all had a significant change over time (p < .05) during the task. The significant change of oculometric measurements indicates oculometrics could be used to detect changes in vigilance for military operators. Future research is needed to assess real-time effects of these oculometrics on performance, especially in a real-world setting.     

The teacher-pupil interaction scale: An empirical method for analyzing the interactive effects of teacher and pupil behavior

The Teacher-Pupil Interaction Scale was developed for use by educational consultants to provide teachers with systematic data for analyzing and improving the learning of pupils. The scoring protocol provides for the simultaneous rating of sequential teacher-pupil interactions; a single mark is used to designate both teacher and pupil behavior at each five-second interval. Observations of a target pupil are alternated with other pupils in the classroom to serve as a point of comparison with the target pupil and to provide a general assessment of the classroom climate. Using the sequential record of their verbal and nonverbal interactions with students, teachers can pinpoint conditions serving both as antecedents and consequents of current student behavior. Armed with this information, teachers can effect changes in their instructional program to increase the rate of desired behaviors and eliminate or reduce unwanted responses.     

Systematic influence of gaze position on pupil size measurement: analysis and correction

Cognitive effort is reflected in pupil dilation, but the assessment of pupil size is potentially susceptible to changes in gaze position. This study exemplarily used sentence reading as a stand-in for paradigms that assess pupil size in tasks during which changes in gaze position are unavoidable. The influence of gaze position on pupil size was first investigated by an artificial eye model with a fixed pupil size. Despite its fixed pupil size, the systematic measurements of the artificial eye model revealed substantial gaze-position-dependent changes in the measured pupil size. We evaluated two functions and showed that they can accurately capture and correct the gaze-dependent measurement error of pupil size recorded during a sentence-reading and an effortless z-string-scanning task. Implications for previous studies are discussed, and recommendations for future studies are provided.     

The Interrater Reliability of Subjective Assessments of the Babinski Reflex

The Babinski reflex is a clinical diagnostic tool; however, the interrater reliability of this tool is currently greatly contested. A comparison between rater groups with objective measurements of the Babinski reflex was therefore conducted. Fifteen recorded Babinski reflexes were assessed by 12 neurologists and 12 medical students as being either pathological or nonpathological. Kinematic and electromyographic variables were collected and used to assess which aspects of the Babinski reflex predict classification. Substantial interrater agreement within the neurologist and student groups (κ = .72 and .67, respectively) was shown; however, there were some differing aspects between what neurologists and students used to assess the reflex as determined by objective kinematic measurements.     

Mapping and correcting the influence of gaze position on pupil size measurements

Pupil size is correlated with a wide variety of important cognitive variables and is increasingly being used by cognitive scientists. Pupil data can be recorded inexpensively and non-invasively by many commonly used video-based eye-tracking cameras. Despite the relative ease of data collection and increasing prevalence of pupil data in the cognitive literature, researchers often underestimate the methodological challenges associated with controlling for confounds that can result in misinterpretation of their data. One serious confound that is often not properly controlled is pupil foreshortening error (PFE)—the foreshortening of the pupil image as the eye rotates away from the camera. Here we systematically map PFE using an artificial eye model and then apply a geometric model correction. Three artificial eyes with different fixed pupil sizes were used to systematically measure changes in pupil size as a function of gaze position with a desktop EyeLink 1000 tracker. A grid-based map of pupil measurements was recorded with each artificial eye across three experimental layouts of the eye-tracking camera and display. Large, systematic deviations in pupil size were observed across all nine maps. The measured PFE was corrected by a geometric model that expressed the foreshortening of the pupil area as a function of the cosine of the angle between the eye-to-camera axis and the eye-to-stimulus axis. The model reduced the root mean squared error of pupil measurements by 82.5 % when the model parameters were pre-set to the physical layout dimensions, and by 97.5 % when they were optimized to fit the empirical error surface.     

瞳孔变化在记忆加工中的生物标记作用

瞳孔在不同记忆任务的同一加工阶段内具有变化模式的一致性, 瞳孔的缩放变化反映了信息加工过程中神经系统的激活状态。在刺激呈现前的预编码阶段, 瞳孔随个体注意集中水平的提高而收缩。在信息编码阶段, 瞳孔扩张程度作为相继记忆效应的生物标记, 可预测信息未来提取阶段的回忆成绩。在信息提取阶段, 采用自由回忆任务时, 瞳孔随记忆负荷的释放而迅速收缩, 但每个项目的提取均会引发小幅度瞳孔扩张; 而在再认提取任务中, 呈现旧刺激比呈现新刺激时瞳孔扩张更明显, 产生瞳孔新旧效应。瞳孔是记忆加工中敏感而稳定的生物标记, 而瞳孔测量法是探究记忆加工生理机制的有效手段。未来可以从瞳孔追踪术的角度, 采用多种研究手段进一步探究记忆的生理机制。     

Use of the conditional reflex to assess the temporal characteristics of curarization effects on heart rate responding

A Pavlovian methodological counterpart to the use of druginduced changes in operant rates of responding was used to assess the temporal characteristics of d-tubocurarine chloride effects on the heart rate conditional reflex in rats. After a stable conditional reflex had been established, the base heart rate, as well as the unconditional and conditional reflex, was monitored during administration of the drug. A sizable behavioral effect was reflected in all three measures, including a temporary abolition of the conditional and unconditional reflexes. An interpretation of these results was discussed, and further development and application of this specific methodology was explored.     

A portable,unobtrusive device for videorecording clinical interactions

Recording and analyzing real-time interactions in clinical settings is important for basic and applied research in psychology and other disciplines. Investigators frequently have used simple audiotaping procedures to record these encounters (e.g., Roter, Geller, Bernhardt, Larson, & Doksum, 1999), but videorecording is increasingly viewed as more reliable and valid, because it captures the full range of complex and interdependent verbal and nonverbal behaviors that occur in an interaction. This article describes a system designed to videotape clinical interactions in a manner that can be moved in and out of different clinical rooms to preserve flexibility in its use. Data are presented to demonstrate that the system is unobtrusive during the interaction, yet fully compatible with institutional review board guidelines to protect human participants’ privacy and freedom to control the recording process.     

Eye tracking under dichoptic viewing conditions: a practical solution

In several research contexts it is important to obtain eye-tracking measures while presenting visual stimuli independently to each of the two eyes (dichoptic stimulation). However, the hardware that allows dichoptic viewing, such as mirrors, often interferes with high-quality eye tracking, especially when using a video-based eye tracker. Here we detail an approach to combining mirror-based dichoptic stimulation with video-based eye tracking, centered on the fact that some mirrors, although they reflect visible light, are selectively transparent to the infrared wavelength range in which eye trackers record their signal. Although the method we propose is straightforward, affordable (on the order of US$1,000) and easy to implement, for many purposes it makes for an improvement over existing methods, which tend to require specialized equipment and often compromise on the quality of the visual stimulus and/or the eye tracking signal. The proposed method is compatible with standard display screens and eye trackers, and poses no additional limitations on the quality or nature of the stimulus presented or the data obtained. We include an evaluation of the quality of eye tracking data obtained using our method, and a practical guide to building a specific version of the setup used in our laboratories.     

A critical review of the assumptions underlying drug testing

Current drug screening programs are based on a set of assumptions: That drug use adversely affects productivity, that available tests are accurate and cost-effective means of detecting and reducing drug use, and that drug testing is legal. When analyzed in the light of available evidence, little support was found for these assumptions. Used properly, drug testing may play a role in the overall management of employee performance; used improperly, it represents a profound threat to individual rights. Recommendations for additional research and for employers planning to use drug screening are offered.     

Building Schools of Character: A Case‐Study Investigation of Character Education's Impact on School Climate,Pupil Behavior,and Curriculum Delivery

Within an action research framework, this investigation used a mixed‐method case‐study approach to investigate what impact character education has on school climate and pupil behavior within a primary school situated in an Education Action Zone of East Anglia, England. Both quantitative and qualitative data sets suggest that the implementation of a multicomponent socioculturally inspired character‐education program can have positive effects on school climate, pupil behavior, and staff morale. In addition, the findings indicate that there is a positive effect on the school's ability to meet the social, emotional, and cognitive needs of pupils following the implementation of a whole‐school prosocial development program rooted in empirical evidence from psychological and educational research.     

An experimentally confirmed statistical model on arm movement

The purpose of this research work was to develop a methodology to model arm movement in normal subjects and neurologically impaired individuals through the application of a statistical modelling method. Thirteen subjects with Parkinson's disease and 29 normal controls were recruited to participate in an arm motor task. An infrared optoelectronic kinematic movement analysis system was employed to record arm movement at 50 times per second. This study identified the modified extended Freundlich model as one that could be used to describe this task. Results showed that this model fit the data well and that it has a good correspondence between the observed and the predicted data. However, verification of the model showed that the residuals contained a sizeable autocorrelation factor. The Cochrane and Orcutt method was applied to remove this factor, which improved the fit of the model. Results showed that Parkinson's disease subjects had a higher autocorrelation coefficient than the normal subjects for this task. A positive correlation (r(s) = 0.72, p < 0.001) was found between the Langton-Hewer stage and the autocorrelation coefficient of PD subjects. This finding suggests that if autocorrelation is positively correlated with disease progression, clinicians in their clinical practice might use the autocorrelation value as a useful indicator to quantify the progression of a subjects' disease. Significant differences in model parameters were seen between normal and Parkinson's disease subjects. The use of such a model to represent and quantify movement patterns provides an important base for future study.     

Respiratory conditional reflex formation with CO2 and electric shock as unconditional stimuli

In 12 birds used in a CO₂ conditioning experiment there was no evidence of the formation of either a respiratory or a cardiac conditional reflex. Tone and light separately or together were used as conditional stimuli. CS-US intervals ranging from 0.5 to 10 seconds were used. CO₂ concentrations up to 7.4% were also employed. In the shock conditioning experiments six of seven birds showed a respiratory change to the conditional stimulus. In one pigeon perfect differentiation was obtained between the reinforced and nonreinforced tones. The marked difference in conditionability of sensory and chemical stimuli to the “respiratory center” is discussed in relation to the central nervous system connections of the respiratory control mechanism.     

Parameters affecting gap detection in the rat

The present research used a startle amplitude reduction paradigm to investigate the ability of the rat’s auditory system to track rapidly changing acoustic transients. Specifically examined was the ability of brief gaps in otherwise continuous noise to reduce the amplitude of a subsequently elicited acoustic startle reflex. The duration of the gap, time between gap offsetand startle elicitation (the interstimulus interval or ISI), and rise-fall characteristics of the gap were systematically varied. Consistent with previous research, gaps reliably reduced startle amplitude. Gaps 2 msec long were reliably detected, and a 50-msec ISI resulted in the greatest amplitude reduction. Gaps presented at short ISIs produced amplitude reduction that followed a different time course than did gaps presented at longer ISIs. These results may reflect differences in the length oftime available for the processing of the stimulus and may involve two different processes.     

The wide-angle reflection eye camera for visual choice and pupil size

A new equipment has been devised to photograph the reflection of the stimulus scene in the eye. The resulting motion pictures show the pupil encircling the area of the scene which was being fixated by the gaze; they also show the pupil size. Both measurements are simplified by providing a calibrated edge to the scene. No bite bar is required, and the equipment is quick and easy to use, being especially suitable for young children and also for monkeys.