Looking left with left neglect: The role of spatial attention when active vision selects local image features for fixation

Exploring the world with Bálint syndrome: biased bottom-up guidance of gaze by local saliency differences

“…Figure 4 shows polynomial functions of ER as compared to healthy participants and neglect patients. as reported previously (Ptak et al 2009), neglect patients tended to look at regions located in the left half of the image only when these regions had particularly high luminance, but low edge content. the polynomial functions generated from ER's data were strongly U-shaped and showed significant deviations (p < .01) from the pattern of control participants for all four local features.…”

“…Finally, edge content was extracted by convolving the original image using the 'canny' edge detection algorithm (canny 1986) implemented in Matlab ® Image Processing toolbox. and seven neglect patients tested in our previous study (Ptak et al 2009). statistical comparisons were performed using a Bayesian approach for small samples.…”

“…Material and procedure were as described in a previous study (Ptak et al 2009), which involved 18 healthy controls and 13 right-hemisphere stroke patients (six without and seven with left spatial neglect). twenty colour photographs depicting roughly symmetrical portraits of natural scenes, architecture or regular patterns were shown on a 21″ cRt for 15 s each.…”

“…spatial and temporal parameters of saccades and fixations were then computed for each participant. local image features were extracted from patches of 1° × 1° drawn around each fixation and computed as described previously (Ptak et al 2009). Briefly, local luminance was calculated as the average intensity of all pixels within the patch scaled to the mean luminance of the whole image.…”

The role of visual saliency for the allocation of attention: Evidence from spatial neglect and hemianopia

“…In neglect patients the local feature characteristics differ as a function of the horizontal position of fixations. These patients look at regions in the left part of an image that are characterized by increased local luminance, but less edge information (Ptak et al, 2009). They also have a stronger tendency to direct gaze toward irrelevant contralateral distracters when these have higher luminance or different orientation than the remaining items in a search display (Bays et al, 2010).…”