When searching for items in memory, people explore internal representations in much the same way that animals forage in space. Results from a number of fields support this notion at a deeper level of evolutionary homology, with evidence that goal-directed cognition is an evolutionary descendent of animal foraging behavior (Hills, 2006). Is it possible then that humans forage in memory using similar search policies to the way that animals forage in space? To investigate this, we examine how people retrieve items from memory in the category fluency task: Participants were asked to retrieve as many types of animals from memory as they could in 3 minutes. Clusters or patches of these items, along with their semantic similarity and frequency, were found with an automatic Wikipedia corpus analysis using the BEAGLE semantic memory model (Jones & Mewhort, 2007), and via hand-coded category membership from Troyer et al. (1997). Participants did not seem to use static patch boundaries, such as 'pets', to search memory, but instead used fluid patch boundaries that were updated with each new item retrieved. We found that participants leave patches in memory when the marginal (i.e., current) rate of finding items is near the average rate for the entire task, as predicted by optimal foraging theory. Furthermore, participants appear to search within patches using item similarity, but decide where to "land" when moving between patches using item frequency.

Objective To evaluate the association of subretinal hyper-reflective material (SHRM) with visual acuity (VA), geographic atrophy (GA) and scar in the Comparison of Age related Macular Degeneration Treatments Trials (CATT) Design Prospective cohort study within a randomized clinical trial. Participants The 1185 participants in CATT. Methods Participants were randomly assigned to ranibizumab or bevacizumab treatment monthly or as-needed. Masked readers graded scar and GA on fundus photography and fluorescein angiography images, SHRM on time domain (TD) and spectral domain (SD) optical coherence tomography (OCT) throughout 104 weeks. Measurements of SHRM height and width in the fovea, within the center 1mm2, or outside the center 1mm2 were obtained on SD-OCT images at 56 (n=76) and 104 (n=66) weeks. VA was measured by certified examiners. Main Outcome Measures SHRM presence, location and size, and associations with VA, scar, and GA. Results Among all CATT participants, the percentage with SHRM at enrollment was 77%, decreasing to 68% at 4 weeks after treatment and 54% at 104 weeks. At 104 weeks, scar was present more often in eyes with persistent SHRM than eyes with SHRM that resolved (64% vs. 31%; p<0.0001). Among eyes with detailed evaluation of SHRM at weeks 56 (n=76) and 104 (n=66), mean [SE] VA letter score was 73.5 [2.8], 73.1 [3.4], 65.3 [3.5], and 63.9 [3.7] when SHRM was absent, present outside the central 1mm2, present within the central 1mm2 but not the foveal center, or present at the foveal center (p=0.02). SHRM was present at the foveal center in 43 (30%), within the central 1mm2 in 21 (15%) and outside the central 1mm2 in 19 (13%). When SHRM was present, the median maximum height in microns under the fovea, within the central 1 mm2 including the fovea and anywhere within the scan was 86; 120; and 122, respectively. VA was decreased with greater SHRM height and width (p<0.05). Conclusions SHRM is common in eyes with NVAMD and often persists after anti-VEGF treatment. At 2 years, eyes with scar were more likely to have SHRM than other eyes. Greater SHRM height and width were associated with worse VA. SHRM is an important morphological biomarker in eyes with NVAMD.

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Readmissions and complications following cholecystectomy are common and associated with patient and disease characteristics.