Effects of overt and covert attention on the steady-state visual evoked potential

Walter, Sabrina; Quigley, Cliodhna; Andersen, Søren K.; Mueller, Matthias

doi:10.1016/j.neulet.2012.05.011

Cited by 57 publications

(46 citation statements)

References 19 publications

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“…Our findings in overt attention are consistent with a number of other studies [13] that SSVEP modulation is larger in overt compared to covert attention. However, one argument would be whether or not the signals obtained from gazing at the flickering stimulus can be assigned to the attention function and not response of visual cortex to the light, perse.…”

Section: Discussionsupporting

confidence: 93%

SSVEP-modulation by covert and overt attention: Novel features for BCI in attention neuro-rehabilitation

Ordikhani-Seyedlar

Sørensen

Kjær

et al. 2014

2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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In this pilot study the effect of attention (covert and overt) on the signal detection and classification of steady-state visual-evoked potential (SSVEP) were investigated. Using the SSVEP-based paradigm, data were acquired from 4 subjects using 3 scalp electroencephalography (EEG) electrodes located on the visual area. Subjects were instructed to perform the attention task in which they attended covertly or overtly to either of the stimuli flickering with different frequencies (6, 7, 8 and 9Hz). We observed a decrease in signal power in covert compared to the overt attention. However, there was a consistent pattern in covert attention causing an increase in the power of the 2(nd) harmonic of the attended frequency. Encouraging results of this preliminary study indicates that it can be adapted and implemented in the brain-computer interface (BCI) system which could potentially be used as a neuro-rehabilitation tool for individuals with attention deficit.

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Section: Discussionsupporting

confidence: 93%

SSVEP-modulation by covert and overt attention: Novel features for BCI in attention neuro-rehabilitation

Ordikhani-Seyedlar

Sørensen

Kjær

et al. 2014

2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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“…Studies show low frequencies give higher responses as compared to high frequency stimuli, though the latter are more comfortable with subjects. Investigations done on overt and covert attention shows that SSVEP is more reliable with overt attention and covert attention amplitudes are far smaller than overt mode [39].…”

Section: Introductionmentioning

confidence: 93%

“…Recent research studies have shown that the amplitude of the response in the specific stimulus frequency varies with the different subject, colour, intensity and the type of stimulus [6,29,39]. A survey on popular devices used for creating visual stimulus such as cathode-ray-tubes (CRT), liquid crystal display (LCD), thin film transistor (TFT) display and light emitting diode (LED) based sources, identifies LED based visual stimulus as having higher bit rates when compared to other forms [45].…”

Section: Related Workmentioning

confidence: 99%

A Configurable, Inexpensive, Portable, Multi-channel, Multi-frequency, Multi-chromatic RGB LED System for SSVEP Stimulation

Mouli

Palaniappan

Sillitoe

2014

Brain-Computer Interfaces

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Steady state visual evoked potential (SSVEP) is extensively used in the research of brain-computer interface (BCI) and require a controllable and configurable light source. SSVEP requires appropriate control of visual stimulus parameters, such as flicker frequency, light intensity, multi-frequency light source and multi-spectral compositions. Light emitting diodes (LEDs) are extensively used as a light source as they are energy efficient, low power, multi-chromatic, have higher contrast, and support wider frequency ranges. Here, we present the design of a compact versatile visual stimulus which is capable of producing simultaneous multiple frequency RGB LED flicker suitable for a wide range of SSVEP paradigms. The hardware is based upon the open source Arduino platform and supports on-the-fly reprogramming with easily configurable user interface via USB. The design provides fourteen independent high output channels with customisable output voltages. The flicker frequencies can be easily customised within the frequency range of 5-50 Hz, using a look-up table. The LED flickers are generated with single RGB LEDs which generate the required colour or frequency combinations for combined multi-frequency flicker with variable duty cycle to generate SSVEP. Electroencephalogram (EEG) signals have been successfully recorded from five subjects using the stimulator for different frequencies, colours, duty cycle, intensity and multiple frequency RGB source, thereby demonstrating the high usability, adaptability and flexibility of the stimulator. Finally we discuss the possible improvements to the stimulator which could provide real time user feedback to reduce visual fatigue and so increase the level of user comfort.

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“…The commonly used EEG based BCI paradigm which has been very responsive is the steady state visual evoked potential (SSVEP), which is a repetitive sinusoidal like waveform with its frequency synchronised with the frequency of the visual stimulus and recorded from the visual cortex noninvasively [9][10][11][12][13][14]. SSVEP requires a visual stimulus to evoke the potential in the brain and the past studies have shown that the participant responses vary with different type of stimuli based on colour, frequency and intensity [14][15][16][17][18][19][20]. Even though SSVEP requires minimum number of channels and relatively less user training, it is not always comfortable for the user for prolonged usage [9,18].…”

Section: Introductionmentioning

confidence: 99%

Quantification of SSVEP responses using multi-chromatic LED stimuli: Analysis on colour, orientation and frequency

Mouli

Palaniappan

Sillitoe

et al. 2015

2015 7th Computer Science and Electronic Engineering Conference (CEEC)

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Most LED visual stimulators used in steady state visual evoked potential (SSVEP) brain-computer interface (BCI) use single LED sources to elicit SSVEP responses. In this study, we tested the hypothesis that different orientations would have different responses in different participants and aimed to develop a portable LED based stimulus design which consists of a small number of RGB LEDs arranged in a line which can be oriented horizontally or vertically. The colour and frequency of the flicker were controlled by a portable microcontroller platform. The study investigated the performance of the SSVEP from five participants when the LED stimulus was displayed vertically and horizontally for a period of 30 seconds. The frequency range used was from 7 Hz to 11 Hz with three primary colours: red, green and blue in both orientations. Furthermore, we also compared the effect of vertical and horizontal orientations using four different frequencies and three colours to test visual fatigue reduction. The results of the analysis using band-pass filtering and Fast Fourier Transform showed that the green horizontal LED stimulus orientation gave the highest response and viewing comfort in all the participants rather than the vertical orientation.

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Effects of overt and covert attention on the steady-state visual evoked potential

Cited by 57 publications

References 19 publications

SSVEP-modulation by covert and overt attention: Novel features for BCI in attention neuro-rehabilitation

SSVEP-modulation by covert and overt attention: Novel features for BCI in attention neuro-rehabilitation

A Configurable, Inexpensive, Portable, Multi-channel, Multi-frequency, Multi-chromatic RGB LED System for SSVEP Stimulation

Quantification of SSVEP responses using multi-chromatic LED stimuli: Analysis on colour, orientation and frequency

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