Spatial attention shifts receptive fields in monkey extrastriate visual cortex toward the focus of attention (S. Ben Hamed, J. R. Duhamel, F. Bremmer, & W. Graf, 2002; C. E. Connor, J. L. Gallant, D. C. Preddie, & D. C. Van Essen, 1996; C. E. Connor, D. C. Preddie, J. L. Gallant, & D. C. Van Essen, 1997; T. Womelsdorf, K. Anton-Erxleben, F. Pieper, & S. Treue, 2006). This distortion in the retinotopic distribution of receptive fields might cause distortions in spatial perception such as an increase of the perceived size of attended stimuli. Here we test for such an effect in human subjects by measuring the point of subjective equality (PSE) for the perceived size of a neutral and an attended stimulus when drawing automatic attention to one of two spatial locations. We found a significant increase in perceived size of attended stimuli. Depending on the absolute stimulus size, this effect ranged from 4% to 12% and was more pronounced for smaller than for larger stimuli. In our experimental design, an attentional effect on task difficulty or a cue bias might influence the PSE measure. We performed control experiments and indeed found such effects, but they could only account for part of the observed results. Our findings demonstrate that the allocation of transient spatial attention onto a visual stimulus increases its perceived size and additionally biases subjects to select this stimulus for a perceptual judgment.

Abstract. We present a new approach for cryptographic end-to-end verifiable optical-scan voting. Ours is the first that does not rely on a single point of trust to protect ballot secrecy while simultaneously offering a conventional single layer ballot form and unencrypted paper trail. We present two systems following this approach. The first system uses ballots with randomized confirmation codes and a physical in-person dispute resolution procedure. The second system improves upon the first by offering an informational dispute resolution procedure and a public paper audit trail through the use of self-blanking invisible ink confirmation codes. We then present a security analysis of the improved system.

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Wahlen bringen den Willen des Volkes zum Ausdruck und stellen damit einen fundamentalen Baustein für jede Demokratie dar. Forderungen nach einer schnelleren Auszählung haben dazu geführt, dass vermehrt Wahlmaschinen Einsatz finden, trotz der massiven Kritik, die von verschiedenen Seiten geäußert wird. Der Beitrag stellt ein kryptographisches Verfahren vor, das Wahlen mit Wahlmaschinen erlaubt, ohne dabei an Transparenz und Nachvollziehbarkeit einzubüßen. Das Verfahren wurde mit dem Deutschen IT-Sicherheitspreis 2008 ausgezeichnet.