Several recent studies have demonstrated that addicts behave less flexibly than healthy controls in the probabilistic reversal learning task (PRLT), in which participants must gradually learn to choose between a probably rewarded option and an improbably rewarded one, on the basis of corrective feedback, and in which preferences must adjust to abrupt reward contingency changes (reversals). In t...

Behavioral flexibility is considered an important trait for adapting to environmental change, but it is unclear what it is, how it works, and whether it is a problem solving ability. I investigated behavioral flexibility and problem solving experimentally in great-tailed grackles, an invasive bird species and thus a likely candidate for possessing behavioral flexibility. Grackles demonstrated b...

In a recent paper, Malament (2004) employs a time reversal transformation that differs from the standard one, without explicitly arguing for it. This is a new and important understanding of time reversal that deserves arguing for in its own right. I argue that it improves upon the standard one. Recent discussion has focused on whether velocities should undergo a time reversal operation. I addre...

Different subregions of nucleus accumbens (NAc) have been implicated in reward seeking, promoting flexible approach responses, suppressing nonrewarded actions, and facilitating shifts between different discrimination strategies. Interestingly, the NAc does not appear to mediate shifting between stimulus-reward associations (i.e., reversal learning) when reinforcement is predictable. How these n...

Understanding the allocation of skilled labor across industries is necessary to explain inter-industry wage differences and the effect of trade on wages. This paper develops an assignment model with both labor and non-labor inputs in which the assignment of heterogeneous labor across sectors is driven by variation in non-labor input productivity. A scale of operations effect causes high skill a...

Cognitive flexibility (i.e. the ability to adapt goal-directed behaviour in response to changed environmental demands) has repeatedly been shown to depend on the prefrontal cortex (PFC). Recent data from primate studies moreover show that depletion of prefrontal 5-HT impairs reversal learning of visual stimuli [Clarke HF, Walker SC, Crofts HS, Dalley JW, Robbins TW, Roberts AC. Prefrontal serot...

We propose a protocol (called RBO) for broadcasting long streams of single-packet messages over radio channel for tiny, battery powered, receivers. The messages are labeled by the keys from some linearly ordered set. The sender repeatedly broadcasts a sequence of many (possibly millions) of messages, while each receiver is interested in reception of a message with a specified key within this se...

An elusive permutation group is a transitive permutation group with no fixed point free elements of prime orders. In this paper we proved that each minimal normal subgroup of an elusive permutation group with squarefree degree is abelian. As an almost immediate consequence, it follows that there are no elusive permutation groups of degree 2pq where p, q are distinct odd primes.

Since the fall of parity in electroweak interactions the discrete transformations of parity, charge conjugation and time reversal are under close scrutiny for any sign of deviation from maximality where symmetry breaking seems to be complete (like P violation in β decay) and for any sign of symmetry breaking when this has not yet been observed (like T violation in

This work presents the results of indoor wideband measurements investigating the spacetime properties of wireless signal transmission with online time reversal precoding. The measurements were conducted using a new time-reversal wideband MIMO channel sounder operating at 2.45 GHz with a bandwidth of 240 MHz. Both line of sight and non line of sight propagation conditions were investigated. Spat...