The influence of calibration method and eye physiology on eyetracking data quality

Recording eye movement data with high quality is often a prerequisite for producing valid and replicable results and for drawing well-founded conclusions about the oculomotor system. Today, many aspects of data quality are often informally discussed among researchers but are very seldom measured, quantified, and reported. Here we systematically investigated how the calibration method, aspects of participants’ eye physiologies, the influences of recording time and gaze direction, and the experience of operators affect the quality of data recorded with a common tower-mounted, video-based eyetracker. We quantified accuracy, precision, and the amount of valid data, and found an increase in data quality when the participant indicated that he or she was looking at a calibration target, as compared to leaving this decision to the operator or the eyetracker software. Moreover, our results provide statistical evidence of how factors such as glasses, contact lenses, eye color, eyelashes, and mascara influence data quality. This method and the results provide eye movement researchers with an understanding of what is required to record high-quality data, as well as providing manufacturers with the knowledge to build better eyetrackers.     

Do hands attract attention?

Social stimuli, like faces (Kanwisher, McDermott, & Chun, 1997) or bodies (Downing, Jiang, Shuman, & Kanwisher, 2001), engage specific areas within the visual cortex. Behavioural research reveals an attentional bias to these same stimuli (Ro, Friggel, & Lavie, 2007). The current study examined whether there is an attentional bias towards hands, and whether such a bias is distinct from any bias towards human bodies. In a two-alternative, forced-choice dot-probe task, participants saw two side-by-side pictures for 500 ms. A probe dot then appeared on either side and participants indicated where the dot appeared. Participants were significantly faster to respond when the probe location coincided with the location of pictures of bodies, hands, or feet, compared to dogs, starfish, hand tools, toaster ovens, inverted hands, or inverted bodies. Results suggest an attentional bias to bodies and body parts but found no evidence of a difference in attentional advantage of hands over bodies or feet.     

The heart beat does not make us tick: The impacts of heart rate and arousal on time perception

According to popular models of human time perception, variations in prospective timing are caused by two factors: the pulse rate of an internal pacemaker and the amount of attention directed to the passage of time. The results concerning the effect of attention on subjective timing have been conclusive, but the mechanisms that drive the pacemaker are still far from being understood. In two experiments, we examined the impact of two factors that in the existing literature on human time perception have been argued to affect such a pacemaker: arousal and heart rate. Experienced arousal and heart rate were varied independently by means of specific physical exercises: (a) A muscle exercise increased arousal and heart rate; (b) a breath-holding exercise increased arousal but decreased heart rate; and (c) in the control condition, arousal and heart rate were held constant. The results indicate that increased subjective arousal leads to higher time estimates, whereas heart rate itself has no relevant impact on time perception. The results are discussed with respect to the underlying mechanisms of prospective time perception.     

Seeing what you hear: Visual feedback improves pitch recognition

The present study examined the effect of visual feedback on the ability to recognise and consolidate pitch information. We trained two groups of nonmusicians to play a piano piece by ear, having one group receiving uninterrupted audiovisual feedback, while allowing the other only to hear, but not see their hand on the keyboard. Results indicate that subjects for whom visual information was deprived showed significantly poorer ability to recognise pitches from the musical piece they had learned. These results are interesting since pitch recognition ability would not intuitively seem to rely on visual feedback. In addition, we show that subjects with previous experience in computer touch-typing made fewer errors during training when trained with no visual feedback, but did not show improved pitch recognition ability posttraining. Our results demonstrate how sensory redundancy increases robustness of learning, and further encourage the use of audiovisual training procedures for facilitating the learning of new skills.     

Merleau-Ponty’s Responses to Skepticism: A Critical Appraisal

Abstract

In this article, I reconstruct and evaluate Merleau-Ponty’s main responses to philosophical skepticism in the relevant parts of his work. To begin with, I introduce the skeptical argument that Merleau-Ponty most often tried to refute, namely, the dream argument. Secondly, I show how Merleau-Ponty, in his initial works, excludes the skeptical problem by appealing to a general contact with the world guaranteed by perception. Finally, I analyze how in his last texts Merleau-Ponty considers at least some uses of the skeptical arguments as tools to make our opaque contact with being explicit.     

Iconic Prosody in Story Reading

Recent experiments have shown that people iconically modulate their prosody corresponding with the meaning of their utterance (e.g., Shintel et al., 2006). This article reports findings from a story reading task that expands the investigation of iconic prosody to abstract meanings in addition to concrete ones. Participants read stories that contrasted along concrete and abstract semantic dimensions of speed (e.g., a fast drive, slow career progress) and size (e.g., a small grasshopper, an important contract). Participants read fast stories at a faster rate than slow stories, and big stories with a lower pitch than small stories. The effect of speed was distributed across the stories, including portions that were identical across stories, whereas the size effect was localized to size‐related words. Overall, these findings enrich the documentation of iconicity in spoken language and bear on our understanding of the relationship between gesture and speech.     

A Swedish validation of the Berlin Numeracy Test

Recent research has highlighted the importance of considering an individual's level of numeracy, that is their numerical abilities, in a vast variety of judgment and decision making tasks. To accurately evaluate the influence of numeracy requires good and valid measures of the construct. In the present study we validate a Swedish version of the Berlin Numeracy Test (Cokely, Galesic, Schulz, Ghazal & Garcia‐Retamero, 2012). The validation was carried out on both a student sample and a sample representative of the Swedish population. The Swedish BNT showed sound psychometrical properties in both samples. Further, in both samples the BNT had satisfactory convergent and discriminant validity when correlating with other measures of numeracy, while not being significantly related to measures of personality. With respect to predictive validity the results indicated divergent patterns in the two samples. In the student sample, participants scoring highest on the BNT outperformed those in the other three levels, which did not differ in performance. In contrast, in the population sample participants scoring lowest on the BNT performed worse than those in the other three levels, which did not differ in performance. Taken together, however, the results suggest that the Swedish version of the BNT should be considered a valid measure of numeracy in both Swedish student and population representative samples.