You Are Right!

In the social Simon task, two participants perform a spatial compatibility task together, each of them responding to only one stimulus (e.g., one participant reacts to red, the other to green stimuli). Participants show joint spatial compatibility effects (SCEs), that is, they respond faster when their go-stimulus appears on their half of the screen. Effects are absent when the same go/no-go task is performed without a coactor. Joint SCEs were originally explained in terms of shared task representations, but recent research suggests that effects result from spatial response coding: in joint go/no-go tasks, participants perceive themselves as the right/left participant operating a right/left response key. While previous research showed that the spatial alignment of keys and seats influences the effect, the present research demonstrates that merely instructing participants to be the right/left participant operating a right/left response key instead of labeling participants and keys with arbitrary numbers substantially increases joint SCEs.

Exploration of the forbidden regions of the Ramachandran plot (ϕ-ψ) with QTAIM

Left: Response β is defined as: β = arccos(e̲2·y̲) with β* = arccos(e̲1·y̲). Right: QTAIM interpreted Ramachandran plots {(βϕ,βϕ*)-(βψ,βψ*)} ‘-’ is a hyphen and not a subtraction sign. Pale green and dark green crosses indicate the glycine, pink and red pluses represent the remaining amino acids (a.a.) in the magainin peptide structure.

The Canadian Parliamentary Crisis of 2008-09: Searching for a Left Response

Russell, Peter H. and Lorne Sossin, eds. 2009. Parliamentary Democracy in Crisis. Toronto: University of Toronto Press. ISBN: 978-1-4426-1014-9. Paperback: 24.95 CAD. Pages: 201. Topp, Brian. 2010. How We Almost Gave the Tories the Boot: The Inside Story Behind the Coalition. Toronto: Lorimer. ISBN: 978-1-55277-502-8. Paperback: 24.95 CAD. Pages: 192.

“1-2-3”: Is There a Temporal Number Line?

Evidence suggests that numbers are intimately related to space ( Dehaene, Bossini, & Giraux, 1993 ; Hubbard, Piazza, Pinel, & Dehaene, 2005 ). Recently, Walsh (2003) suggested that numbers might also be closely related to time. To investigate this hypothesis we asked participants to compare two digits that were presented in a serial manner, i.e., one after another. Temporally ascending digit pairs (such as 2-3) were responded to faster than temporally descending pairs (3-2). This effect was, in turn, qualified by a local SNARC (spatial numerical association of response codes) effect and a local semantic congruity effect (SCE). Moreover, we observed a global numerical SCE only for temporally descending digit pairs. However, we did not observe a global SNARC effect, i.e., an interaction of numerical magnitude and the right/left response hand. We discuss our results in terms of overlearned forward-associations (“1-2-3”) as formed by our ubiquitous cognitive routines to count off objects or events.

Memory for Reward in Probabilistic Choice: Markovian and Non-Markovian Properties

Pigeons were rewarded with food for pecking keys in various forms of two-armed bandit situation for an extended series of daily sessions in two experiments. The average daily preference (S=R/[R+L]) is very well fit by a markovian linear model in which predicted preference today is an average of predicted preference yesterday and reinforcement conditions today: s(N+1) = as(N) + (1-a)A(N+1), where A(N+1) is set equal to 1 when all rewards are for the Right response, and 0 when all are for the Left, and a is a longterm memory parameter. This linear model explains some apparent paradoxes in earlier reports of memory effects in two-armed bandit experiments. Nevertheless, closer examination of the details of preference changes within each experimental session showed several kinds of non-markovian effects. The most important was a regression at the beginning of each experimental session towards a preference characteristic of earlier sessions (spontaneous recovery). This effect, but not a smaller, less reliable non-markovian reminiscence effect, is consistent with a very simple rule, namely that the effect on preference of each individual reward for a Right or Left response is inversely related to how long ago the reward occurred. Thus, animals learn to prefer the rewarded side each day because these rewards are recent; but they regress to earlier preferences overnight because the most recent rewards become relatively less recent with lapse of time.

Sensed Movement to Sinusoidal Angular and Electrical Stimulation

Three types of stimulation were presented to blindfolded Ss seated in a chair: sinusoidal right-left mechanical rotation; bilateral sinusoidal electrical current via electrodes over the mastoid processes; and simultaneous mechanical and electrical stimulation. Ss signalled perceived right or left rotation by pressing right or left response buttons, respectively. Sensations of rotation were reported to electrical stimulation alone, and appeared to interact in a simple summative manner with sensations produced by mechanical rotation. A biteboard reduced but did not eliminate the electrical effects.