Deciding when to decide : time-variant sequential sampling models explain the emergence of value-based decisions in the human brain

The cognitive and neuronal mechanisms of perceptual decision making have been successfully linked to sequential sampling models. These models describe the decision process as a gradual accumulation of sensory evidence over time. The temporal evolution of economic choices, however, remains largely unexplored. We tested whether sequential sampling models help to understand the formation of value-based decisions in terms of behavior and brain responses. We used functional magnetic resonance imaging (fMRI) to measure brain activity while human participants performed a buying task in which they freely decided upon how and when to choose. Behavior was accurately predicted by a time-variant sequential sampling model that uses a decreasing rather than fixed decision threshold to estimate the time point of the decision. Presupplementary motor area, caudate nucleus, and anterior insula activation was associated with the accumulation of evidence over time. Furthermore, at the beginning of the decision process the fMRI signal in these regions accounted for trial-by-trial deviations from behavioral model predictions: relatively high activation preceded relatively early responses. The updating of value information was correlated with signals in the ventromedial prefrontal cortex, left and right orbitofrontal cortex, and ventral striatum but also in the primary motor cortex well before the response itself. Our results support a view of value-based decisions as emerging from sequential sampling of evidence and suggest a close link between the accumulation process and activity in the motor system when people are free to respond at any time

An efficient Algorithm to partition a Sequence of Integers into Subsets with equal Sums

To partition a sequence of n integers into subsets with prescribed sums is an NP-hard problem in general. In this paper we present an efficient solution for the homogeneous version of this problem; i.e. where the elements in each subset add up to the same sum.Comment: 12 page

Stability boundaries of roll and square convection in binary fluid mixtures with positive separation ratio

Rayleigh-B\'{e}nard convection in horizontal layers of binary fluid mixtures heated from below with realistic horizontal boundary conditions is studied theoretically using multi-mode Galerkin expansions. For positive separation ratios the main difference between the mixtures and pure fluids lies in the existence of stable three dimensional patterns near onset in a wide range of the parameter space. We evaluated the stationary solutions of roll, crossroll, and square convection and we determined the location of the stability boundaries for many parameter combinations thereby obtaining the Busse balloon for roll and square patterns.Comment: 19 pages + 15 figures, accepted by Journal of Fluid Mechanic

The Effect of Central Exit Examinations on Student Achievement: Quasi-experimental Evidence from TIMSS Germany

This paper makes use of the regional variation in schooling legislation within the German secondary education system to estimate the causal effect of central exit examinations on student performance. We propose a difference-in-differences framework that exploits the quasi-experimental nature of the German TIMSS middle-school sample. The estimates show that students in federal states with central exit examinations clearly outperform students in other federal states, but that only part of the difference can be attributed to central exit examinations. Our results suggest that central examinations increase student achievement by about one third school year equivalent.education, central examinations, difference-in-differences, quasi-experiment

Income Mobility in Old Age in Britain and Germany

The increases in human longevity in recent decades and the trends for early retirement have posed new challenges for policy makers, and require a holistic understanding of the processes that influence the economic resources of older people. This paper contributes to this knowledge by examining the income mobility experienced by older people living in Britain and Germany during the 1990s, and by identifying personal attributes and life-course events that influenced its direction and likelihood. The analysis uses the British Household Panel Survey (BHPS) and the German Socio-Economic Panel (SOEP) panel data. The comparative perspective yields insights about the different income experience of older people in the two markedly different welfare regimes. Results show that old-age income mobility is more pronounced in Britain than in Germany, and that in both countries its occurrence is particularly associated with changes in living arrangements, in the employment status of the co-resident family members and with widowhood among women. Unemployment during working life is also associated with significant negative later life income mobility. Among those on low incomes, a high share of income from an earnings-related pension had a significant and positive effect in both countries. One policy implication is the need to strengthen the social safety net, to safeguard against downward income mobility in old age, particularly among widows. Policy incentives are required to encourage flexible living arrangements in old age, as well as a greater protection from unemployment during working life, more so in Germany than in Britain.income mobility, old age, pensions, Britain and Germany

Visual complexity of bike maps

More and more cities try to encourage residents to cycle more. Therefore, governments are developing comprehensive bike maps to facilitate bicycle trip planning and, as a result, increase the popularity of cycling in general (Pucher and Buehler, 2008). However, research on the topic of bike maps is rare and the versatility of possible features shown on a bike map makes these visually more complex than others. It is critical to understand how maps are perceived and understood to improve their overall design and efficiency (Castner and Eastman, 1984). The purpose of this thesis is understand how base maps and the display of various cycling related features a↵ect the visual complexity of bike maps. Different metrics (GMLMT, Subband Entropy, Edge Density, Feature Congestion, and Distinct Object-Type Counts) are applied on bike maps to measure visual map complexity. Following that, an eye-tracking experiment with 35 participants is carried out. Five different everyday tasks have to be solved on bike maps with four complexity levels. The experiment aims to find out how base maps and cycling related features influence the effectiveness of a map. The findings suggest that adding more detail to base maps and displaying more cycling related features on a map resulted in a visually more complex bike map. Size, shape, and color were found to have the biggest influence on the applied metrics. The eye-tracking study discovered that the display of cycling related features can affect the time needed for successful task completion. To deepen the gained understanding, further research should in more detail investigate how base maps influence bike maps efficiency. To gain maximal learning from such studies, large and representative test groups should be examined in a fully randomized manner

Oldies but Goodies: Bloom's Taxanomy as a Guide for Teacher-made Tests

La taxonomie de Bloom peut être utilisée pour de multiples objectifs dans le cadre de la formation initiale des enseignants. Cette contribution propose un exercice d’utilisation de la taxonomie de Bloom pour créer un test, à travers lequel les futurs enseignants réfléchissent à l’adaptation de matériel pré-existant. Cet exercice permet non seulement de penser l’évaluation mais également de considérer l’organisation des savoirs à différents niveaux.+repphzhbib2016

Die Einkommensstruktur der Perforations-Jobs bei perforierter Langzeitarbeitslosigkeit : eine Überprüfung der Leistungsfähigkeit mikroökonomischer Arbeitsmarkttheorien in einem peripheren Job-Segment

"Als perforierte Langzeitarbeitslosigkeit wird ein erwerbsbiographisches Muster bezeichnet, bei dem sich über einen längeren Zeitraum hinweg Phasen der Arbeitslosigkeit mit kurzfristigen Beschäftigungsverhältnissen ('Perforations-Jobs') abwechseln. Die Einkommensstruktur dieser Perforations-Jobs wird analysiert. Ausgangspunkt ist die letzte vor Eintritt in Langzeitarbeitslosigkeit ausgeübte 'reguläre' Beschäftigung ('Ausgangs-Job'). Die Studie basiert auf Daten der Verlaufsstichprobe aus der Beschäftigtenstatistik. Die Perforations-Jobs sind signifikant schlechter bezahlt und qualitativ stärker nivelliert als die Ausgangs-Jobs. Diese Verschiebung wird bereits zu Beginn einer Perforations-Biographie realisiert. Im weiteren Verlauf stabilisiert sich die Einkommensverteilung. Als Perforations-Jobs stehen keineswegs nur schlecht bezahlte 'Hamburger-Jobs' zur Verfügung; es lassen sich die klassischen einkommensbestimmenden Determinanten beobachten. Beim Übergang von Ausgangs-Jobs zum ersten ausgeübten Perforations-Job ergeben sich starke merkmalsspezifische Unterschiede bezüglich des Risikos einer Einkommensverschlechterung. Theoretisch unerwartet ist ein geringeres Verschlechterungsrisiko bei längerer Suchdauer. Im weiteren Verlauf der Perforations-Biographie schwächen sich die beobachteten Verschlechterungsrisiken deutlich ab; erhalten bleibt jedoch der Effekt, daß bei längerer Suchdauer besser dotierte Perforations-Jobs besetzt werden. Die Ergebnisse belegen, daß im untersuchten peripheren Arbeitsmarktsegment humankapitaltheoretische Erklärungsansätze nur in ihrer Ausrichtung (Einkommensdeterminanten), nicht aber in ihrer dynamischen Ausrichtung (Einkommensverluste durch Arbeitslosigkeit) Gültigkeit behalten. Auch die Suchtheorie verliert an Erklärungskraft: Eine höhere Unterstützungsleistung führt nicht zu einer Verlängerung der Suchdauer. Das Gesamtergebnis der Untersuchung ist dagegen segmentationstheoretisch konsistent: Als entscheidend hinsichtlich des Verschlechterungsrisikos wird der - über die Unterstützungsquote nur unzureichend operationalisierte - soziale Druck, ein Job-Angebot schnell und unbesehen seiner Qualität akzeptieren zu müssen, erkannt; zentraler Indikator für die Stärke dieses Drucks ist die sozial tolerierte und/oder finanziell 'durchstehbare' Suchdauer." (Autorenreferat, IAB-Doku)Langzeitarbeitslosigkeit, Mehrfacharbeitslosigkeit, Arbeitsplatzqualität, berufliche Reintegration, Einkommensstruktur, kurzfristige Beschäftigung, Einkommenshöhe - Determinanten