Holding-side influences on infant's view of mother's face.

Recently we found that adult children whose mothers had had a right-arm preference for holding infants have a reduced left bias for recognising faces, suggesting that they are less well right-hemisphere lateralised for perceiving faces. One possible explanation of this finding is that early visual exposure to faces is suboptimal for right-held infants. To test this idea, we asked mothers to pick up a doll with an inbuilt camera in its face and to start bottle-feeding it. The results showed that less was visible of the face of mothers who held the doll on their right arm in comparison to those who held the doll on their left arm: From the right arm, the mother's left half of the face was less visible when the mothers were looking up and their right half of the face was less visible when they were looking at the doll. These results suggest that right-held infants receive suboptimal information from faces. Because early face exposure is important for face-processing development, the suboptimal face exposure probably experienced by right-held infants may have consequences for their ability to recognise faces and facial emotion later in life.

Learning to cooperate without awareness in multiplayer minimal social situations.

Experimental and Monte Carlo methods were used to test theoretical predictions about adaptive learning of cooperative responses without awareness in minimal social situations-games in which the payoffs to players depend not on their own actions but exclusively on the actions of other group members. In Experiment 1, learning occurred slowly over 200 rounds in a dyadic minimal social situation but not in multiplayer groups. In Experiments 2-4, learning occurred rarely in multiplayer groups, even when players were informed that they were interacting strategically and were allowed to communicate with one another but were not aware of the game's payoff structure. Monte Carlo simulation suggested that players approach minimal social situations using a noisy version of the win-stay, lose-shift decision rule, deviating from the deterministic rule less frequently after rewarding than unrewarding rounds.

Evidence for magnocellular involvement in the identification of flanked letters.

Little is known about the role of the magno system in reading. One important hypothesis is that this system is involved in the allocation of attention. We reasoned that the presentation of a single letter automatically draws attention to this letter, whereas in the case of a flanked letter, an additional process of attention allocation is required for identification to occur. In three letter-naming experiments with 24 subjects each, normally reading adults were presented with flanked (e.g. xax) and with single (e.g. a) letters at three possible (para)foveal locations. The letters appeared in magno-disadvantageous colour contrast or in parvo-disadvantageous weak luminance contrast with the background. A control experiment verified that colour contrast had generated less magnocellular activity than had luminance contrast. Colour-contrast presentation led to a significantly lower naming performance for flanked letters than did luminance-contrast presentation, despite the fact that the two contrasts did not elicit differences in naming performance when the letters were presented in isolation. This latter finding rules out the possibility that colour contrast had generated not only less magno- but also less parvocellular activity than had luminance contrast. Thus, it can be concluded that the magno system is involved in the identification of flanked letters. This conclusion supports the hypothesis that the magno system is important to the allocation of attention. Further, it may provide an explanation for the frequent finding that people with developmental dyslexia have impairments in their magnocellular system.

Magnocellular involvement in flanked-letter identification relates to the allocation of attention.

To verify the hypothesis that the magnocellular system is important to flanked-letter identification [Neuropsychologia 40 (2002) 1881] because it subserves attention allocation, we conducted three letter-naming experiments in which we manipulated magnocellular involvement (colour vs. luminance contrast) and prior information regarding target-letter location. Location information was provided through constant presentation at the same location (Experiment 1) or through auditory precueing (Experiments 2 and 3). In control conditions, either no (Experiments 1 and 3) or invalid (Experiment 2) location information was given. In line with the hypothesis, magnocellular input helped flanked-letter identification only when no prior location information was given.