Fairness Motivations and Procedures of Choice between Lotteries as Revealed through Eye Movements

Eye tracking is used to investigate decision makers’ motivations and procedures in choice problems. Patterns of eye movements in problems where the deliberation process is easily discernable are used to understand the deliberation in other problems. We find that in problems which involve the distribution of income between the participant and another individual, participants who behave selfishly nevertheless take into consideration the size of the payment to the other person. In problems that involve choice between two simple lotteries, eye movements indicate that many participants based their decision on a comparison of prizes and probabilities rather than making an expected utility calculation

Manipulations of Wavefront Propagation: Useful Methods and Applications for Interferometric Measurements and Scanning

Phase measurements obtained by high-coherence interferometry are restricted by the 2π ambiguity, to height differences smaller than λ/2. A further restriction in most interferometric systems is for focusing the system on the measured object. We present two methods that overcome these restrictions. In the first method, different segments of a measured wavefront are digitally propagated and focused locally after measurement. The divergent distances, by which the diverse segments of the wavefront are propagated in order to achieve a focused image, provide enough information so as to resolve the 2π ambiguity. The second method employs an interferogram obtained by a spectrum constituting a small number of wavelengths. The magnitude of the interferogram’s modulations is utilized to resolve the 2π ambiguity. Such methods of wavefront propagation enable several applications such as focusing and resolving the 2π ambiguity, as described in the article

Collinear stimuli induce local and cross-areal coherence in the visual cortex of behaving monkeys.

BACKGROUND: Collinear patterns of local visual stimuli are used to study contextual effects in the visual system. Previous studies have shown that proximal collinear flankers, unlike orthogonal, can enhance the detection of a low contrast central element. However, the direct neural interactions between cortical populations processing the individual flanker elements and the central element are largely unknown. METHODOLOGY/PRINCIPAL FINDINGS: Using voltage-sensitive dye imaging (VSDI) we imaged neural population responses in V1 and V2 areas in fixating monkeys while they were presented with collinear or orthogonal arrays of Gabor patches. We then studied the spatio-temporal interactions between neuronal populations processing individual Gabor patches in the two conditions. Time-frequency analysis of the stimulus-evoked VSDI signal showed power increase mainly in low frequencies, i.e., the alpha band (α; 7-14 Hz). Power in the α-band was more discriminative at a single trial level than other neuronal population measures. Importantly, the collinear condition showed an increased intra-areal (V1-V1 and V2-V2) and inter-areal (V1-V2) α-coherence with shorter latencies than the orthogonal condition, both before and after the removal of the stimulus contribution. α-coherence appeared between discrete neural populations processing the individual Gabor patches: the central element and the flankers. CONCLUSIONS/SIGNIFICANCE: Our findings suggest that collinear effects are mediated by synchronization in a distributed network of proximal and distant neuronal populations within and across V1 and V2

α-coherence dynamics in collinear and orthogonal conditions.

<p><i>A</i>: α-coherence as a function of time between V1-CE and other ROIs for the collinear (blue), orthogonal (red) and fixation alone (green) conditions averaged over pixels within each of the 4 ROIs (from left to right): V1-CE (n = 555 pixels), V1-flanker (n = 444 pixels), V2-CE (n = 523 pixels) and V2-Flanker (n = 545 pixels). Dashed lines indicate mean±3×SEM. Black horizontal lines indicate upper and lower limits of the α-coherence (mean±3×SEM) in the fixation alone condition. A change in α-coherence is defined by exceeding these limits. There was significantly higher stimulus-induced α-coherence in both collinear and orthogonal conditions compared to the fixation alone condition (Mann-Whitney U-test; p<0.01; averaged 0–100 ms). The inset depicts the pair of ROIs (blue arrow) from which α-coherence was calculated (see Fig. 1E). <i>B</i>: Scatter plots of the average α-coherence (AAC) averaged 0–100 ms after stimulus onset (shaded bar in A) in the collinear (y-axis) vs. the orthogonal (x-axis) conditions for each pixel in the different ROIs as in A. Each point reflects the average α-coherence of all pixel pairs between this specific pixel (in a specific ROI) and the V1-CE ROI pixels (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049391#pone.0049391.e012" target="_blank">equation 8</a>). Almost all pixels are above the diagonal meaning there is higher AAC in the collinear than the orthogonal condition. <i>C</i>: Histograms of time-to-peak (TTP) differences (orthogonal - collinear) of the α-coherence for the all pixels in the four ROIs as in B. Time = 0 indicates that peak α-coherence was reached at the same time window in both conditions. There is significantly lower TTP in the collinear than the orthogonal condition in each ROI (p<0.001). Data is from 8 recording session and 2 monkeys.</p

α-coherence between different ROIs in V1 and V2.

<p><i>A:</i> A schematic illustration of the 4 ROIs used in this study: V1-CE, V1-flanker, V2-CE and V2-flanker. Superimposed are 4 different interactions each representing a pair of ROIs: V1-CE and V1-flanker (blue), V1-CE and V2-CE (red), V1-flanker and V2-flanker (green), V2-CE and V2-flanker (purple). <i>B:</i> The α-coherence as a function of time for the collinear (solid lines) and orthogonal (dashed lines) conditions calculated between each of the four pairs in A. <i>C:</i> α-coherence difference (collinear – orthogonal) between each of the four pairs in A. α-coherence was average 40–60 ms after stimulus onset (shaded bar in B). Error bars indicate SEM over recording sessions (n = 8 recording session from 2 monkeys). Asterisks denote significant α-coherence compared to 0 or between pairs. * p<0.05; ** p<0.01.</p

α-coherence maps in collinear and orthogonal conditions.

<p><i>A</i>: Average α-coherence (AAC; averaged over 0–100 ms after stimulus onset) maps in the collinear (left) and orthogonal (right) conditions in one recording session. Each pixel in the map reflects the average AAC of that pixel with the ROI of V1-CE in the collinear (left) and orthogonal (right) conditions. Color denotes coherence values. The ROI of V1-CE (solid black ellipse) and the ROI of V1-flanker (dashed black ellipse) are superimposed on all maps. Inset indicates the 4 ROIs: V1-CE (yellow), V1-flanker (green), V2-CE (red) and V2-flanker (purple) for this recording session. <i>B</i>: AAC maps as in A, but for a different recording session with changed positions of CE and flanker.</p