Cherry-picking information: humans actively sample evidence to support prior beliefs

No one likes to be wrong. Previous research has shown that participants may underweight information incompatible with previous choices, a phenomenon called confirmation bias. In this paper we argue that a similar bias exists in the way information is actively sought. We investigate how choice influences information gathering using a perceptual choice task and find that participants sample more information from a previously chosen alternative. Furthermore, the higher the confidence in the initial choice, the more biased information sampling becomes. As a consequence, when faced with the possibility of revising an earlier decision, participants are more likely to stick with their original choice, even when incorrect. Critically, we show that agency controls this phenomenon. The effect disappears in a fixed sampling condition where presentation of evidence is controlled by the experimenter, suggesting that the way in which confirmatory evidence is acquired critically impacts the decision process. These results suggest active information acquisition plays a critical role in the propagation of strongly held beliefs over time.

Propeller Synchrophase Angle Optimization of Turboprop-Driven Aircraft—An Experimental Investigation

Propeller synchrophasing is an effective way of reducing interior noise and vibration of turboprop-driven aircraft. However, synchrophasing has achieved limited success in practice for the reason that the predetermined phase angles are not acoustically optimized for maximum noise reduction during all flight conditions. An investigation has been conducted out which includes two folds: first, the noise vector based on laboratory experimental data has been modeled and second, optimal phase to acquire minimum noise is obtained via optimization search. An improved identification method of vector noise model which can be less dependent to noise phase message is presented. Compared with traditional methods, this method can greatly reduce the real-time requirement between phase optimization model and control model or sound acquiring model, so it can eliminate the influence which communication delay brings on identification precision. A synchrophasing experimental platform is established to verify the vector noise modeling. It adopts two propellers-driven servo motors to simulate the interior noise environment of the aircraft. The influence of the date sampling condition on identification is also researched. Ant colony optimization with two improvements is applied to phase optimization of four propellers. Simulation results show that the improved algorithm requires much less calculation.

Digital-beam-forming extension for a two-channel E-band FMCW-sensor

A general purpose two-channel Frequency modulated continuous wave (FMCW)-sensor in E-band is extended to a digital-beam-forming (DBF) system. The hardware extension contains a transmit multiplexer, which allows switching of the (DBF) transmit signal of the sensor to any of 32 linearly arranged waveguide antennae. To maintain the spatial sampling condition by λ/2 element distance, the antenna ports are arranged in the E-plane. The ports can directly radiate or serve as primary radiators of a cylindrical dielectric lens focusing in the H-plane. By realizing the hardware extension based on a metal-backed substrate, some novel radio frequency (RF) structures became necessary. One of these structures is a special twisting microstrip-to-waveguide-transition to connect the switching matrix to waveguide ports arranged in the E-plane. Key elements of the multiplexer are commercially available pin-diode-based MMIC-switches in microstrip technology. To lower the inductance of the interconnects, they are embedded in cavities in the metal-backed RF-substrate. RF interconnects between the sensor and the extension are all done with waveguide ports. Further interconnects between the module and the extension are low-frequency or digital and are led via cables and removable plugs. Both module and extension can be powered separately. This gives an easily mountable extension for making a two-dimensional (2D) DBF sensor out of a 1D FMCW-sensor.

Understanding the diet composition of marine mammals: grey seals (Halichoerus grypus) in the Baltic Sea

Lundström, K., Hjerne, O., Lunneryd, S-G., and Karlsson, O. 2010. Understanding the diet composition of marine mammals: grey seals (Halichoerus grypus) in the Baltic Sea. – ICES Journal of Marine Science, 67: 1230–1239. Dietary studies are important in understanding the ecological role of marine mammals and in formulating appropriate management plans in terms of their interactions with fisheries. The validity of such studies has, however, often been compromised by unrepresentative sampling procedures, resulting in false weight being given to external factors seeming to influence diet composition. The bias caused by non-random sampling was examined, using canonical correspondence analysis to assess how the prey species composition in digestive tract samples of Baltic grey seals (Halichoerus grypus) was related to spatial, temporal, and demographic factors and to whether the samples were collected in association with fishing gear or not (“sampling condition”). Geographic region explained the largest fraction of the observed variation, followed by sampling condition, age group, and year. Season and gender were not statistically significant. Segregation of the two age categories “pups” and “juveniles–adults”, and the two geographic categories “Baltic proper” and “Gulf of Bothnia” are proposed to estimate the diet and fish consumption of the Baltic grey seal population as a whole. Atlantic herring was the most commonly recovered prey item in all areas and age groups, followed by European sprat in the south, and common whitefish in the north. Pups had eaten relatively more small non-commercial species than older seals.