LCD Monitors as an Alternative for Precision Demanding Visual Psychophysical Experiments

Assessing the Effect of the Refresh Rate of a Device on Various Motion Stimulation Frequencies Based on Steady-State Motion Visual Evoked Potentials

The refresh rate is one of the important parameters of visual presentation devices, and assessing the effect of the refresh rate of a device on motion perception has always been an important direction in the field of visual research. This study examined the effect of the refresh rate of a device on the motion perception response at different stimulation frequencies and provided an objective visual electrophysiological assessment method for the correct selection of display parameters in a visual perception experiment. In this study, a flicker-free steady-state motion visual stimulation with continuous scanning frequency and different forms (sinusoidal or triangular) was presented on a low-latency LCD monitor at different refresh rates. Seventeen participants were asked to observe the visual stimulation without head movement or eye movement, and the effect of the refresh rate was assessed by analyzing the changes in the intensity of their visual evoked potentials. The results demonstrated that an increased refresh rate significantly improved the intensity of motion visual evoked potentials at stimulation frequency ranges of 7-28 Hz, and there was a significant interaction between the refresh rate and motion frequency. Furthermore, the increased refresh rate also had the potential to enhance the ability to perceive similar motion. Therefore, we recommended using a refresh rate of at least 120 Hz in motion visual perception experiments to ensure a better stimulation effect. If the motion frequency or velocity is high, a refresh rate of≥240 Hz is also recommended.

Encouraging Digital Technology in Neuropsychology: The Theory of Visual Attention on Tablet Devices

OBJECTIVE

Visual attention helps us to selectively process relevant information and is crucial in our everyday interactions with the environment. Not surprisingly, it is one of the cognitive domains that is most frequently affected by acquired brain injury. Reliable assessment of attention deficits is pivotal to neuropsychological examination and helps to optimize individual rehabilitation plans. Compared with conventional pen-and-paper tests, computerized tasks borrowed from the field of experimental psychology bring many benefits, but lab-based experimental setups cannot be easily incorporated in clinical practice. Light-weight and portable mobile tablet devices may facilitate the translation of computerized tasks to clinical settings. One such task is based on the Theory of Visual Attention (TVA), a mathematical model of visual attention. TVA-based paradigms have been widely used to investigate several aspects of visual attention in both fundamental and clinical research, and include measures for general processing capacity as well as stimulus-specific attentional parameters.

METHODS

This article discusses the benefits of TVA-based assessments compared with frequently used neuropsychological tests of visual attention, and examines the reliability of a tablet-based TVA-based assessment in 59 neurologically healthy participants.

RESULTS

Pearson's correlations indicate that the tablet-based TVA assessment and the conventional lab-based TVA assessment have a comparable parallel-form (range: .67-.93), test-retest (range: .61-.78), and internal reliability (range: .56-.97).

CONCLUSION

Our results suggest that tablet-based TVA assessment may be a promising tool to acquire clinical measures of visual attention at low cost at the bedside of the patient.

How Monitor Characteristics Affect Human Perception in Visual Computer Experiments: CRT vs. LCD Monitors in Millisecond Precise Timing Research

Liquid crystal display (LCD) monitors are nowadays standard in computerized visual presentation. However, when millisecond precise presentation is concerned, they have often yielded imprecise and unreliable presentation times, with substantial variation across specific models, making it difficult to know whether they can be used for precise vision experiments or not. The present paper intends to act as hands-on guide to set up an experiment requiring millisecond precise visual presentation with LCD monitors. It summarizes important characteristics relating to precise visual stimulus presentation, enabling researchers to transfer parameters reported for cathode ray tube (CRT) monitors to LCD monitors. More importantly, we provide empirical evidence from a preregistered study showing the suitability of LCD monitors for millisecond precise timing research. Using sequential testing, we conducted a masked number priming experiment using CRT and LCD monitors. Both monitor types yielded comparable results as indicated by Bayes factor favoring the null hypothesis of no difference between display types. More specifically, we found masked number priming under conditions of zero awareness with both types of monitor. Thus, the present study highlights the importance of hardware settings for empirical psychological research; inadequate settings might lead to more “noise” in results thereby concealing potentially existing effects.