6 7 Abstract 8 9 We use a Bayesian framework to detect periodic components in fMRI data. The resulting detector 10 is sensitive to periodic components with a flexible number of harmonics and with arbitrary amplitude 11 and phases of the harmonics. It is possible to detect the correct number of harmonics in periodic 12 signals even if the fundamental frequency is beyond the Nyquist frequency. We...

Performance of a wide range of simple visual tasks improves with practice. Here we ask whether such learning occurs for the fundamental visual task of luminance contrast detection. In two experiments we find that contrast sensitivity increases following extensive practice at detecting briefly presented sinusoidal luminance gratings and that learning is maintained after six months. Learning is s...

We measured contrast thresholds for the identification of faces and facial expressions as a function of the center spatial frequency of narrow-band additive noise. In adults, masking of mid spatial frequencies (11-16c/fw) caused the largest elevation in contrast threshold (Experiment 1). Ideal observer analysis revealed that adults were equally sensitive to available information at low and mid ...

In event-related brain potential (ERP) studies using a visual S1-S2 matching task, change stimuli elicit a posterior positivity at around 100-200 ms. In the present study, we investigated the effects of magnitude of spatial frequency changes on change-related positivity. Each trial consisted of two sequentially presented stimuli (S1-S2), where S2 was either (1) the same as S1 (i.e., NO-change, ...

Radio frequency (RF) power is one of the most important quantity in RF metrology. In recent years significant progress has been achieved in developing new primary RF power standards with extended frequency ranges and improved uncertainties. These developments and the results of numerous international comparisons in the field of precise RF power measurements carried out in the last years are rev...

Knowledge of the impact of potential sources of error in spatial frequency domain imaging (SFDI) is essential for the quantitative characterization of absorption and scattering in tissue and other turbid media. We theoretically investigate the error in the derived absorption and scattering parameter, subject to typical experimental and theoretical sources of errors. This provides a guideline to...

We characterised the impact of spatial frequency and contrast on saccade latencies to single Gabor patches. Saccade latencies decreased as a function of contrast, and increased with spatial frequency. The observed latency variations are qualitatively similar to those observed for manual reaction times. For single target detection, our findings highlight the similarity in the visual processes th...