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As Turing (1936, Proceedings of the London Mathematical Society) noted, a fundamental process in human cognition is to effect chained sequential operations in which the second operation requires an input from the preceding one. Although a great deal is known about the costs associated with 'independent' (unrelated) operations, e. g., from the classic psychological refractory period paradigm, far less is known about those operations to which Turing referred. We present the results of two behavioural experiments, where participants were required to perform two speeded sequential tasks that were either chained or independent. Both experiments reveal the reaction time cost of chaining, over and above classical dual-task serial costs. Moreover, the chaining operation significantly altered the distribution of reaction times relative to the Independent condition in terms of an increased mean and variance. These results are discussed in terms of the cognitive architecture underlying the serial chaining of cognitive operations. © 2011 Springer-Verlag. Fil: Fan, Zhao. Huazhong Normal University; China Fil: Singh, Krish. Cardiff University; Reino Unido Fil: Muthukumaraswamy, Suresh. Cardiff University; Reino Unido Fil: Sigman, Mariano. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Neurociencia Integrativa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina Fil: Dehaene, Stanislas. College de France; Francia Fil: Shapiro, Kimron. Bangor University; Reino Unido

The attentional blink (AB) effect demonstrates that when participants are instructed to report two targets presented in a rapid visual stimuli stream, the second target (T2) is often unable to be reported correctly if presented 200-500 msec after the onset of the first target (T1). However, if T2 is presented immediately after T1, in the conventional lag-1 position (100-msec stimulus onset asynchrony; SOA), little or no performance deficit occurs. The present experiments add to the growing literature relating the "lag-1 sparing" effect to T1 masking. Using a canonical AB paradigm, our results demonstrate that T2 performance at lag 1 is significantly reduced in the presence of T1 masking. The implications of this outcome are discussed in relation to theories of the AB.

After the detection of a target item in a rapid stream of visual stimuli, there is a period of 400-600 ms during which subsequent targets are missed. This impairment has been labelled the 'attentional blink'. It has been suggested that, unlike an eye blink, the additional blink does not reflect a suppression of perceptual processing, but instead reflects a loss of information at a postperceptual stage, such as visual short-term memory. Here we provide electrophysiological evidence that words presented during the attentional blink period are analysed to the point of meaning extraction, even though these extracted meanings cannot be reported 1-2s later. This shows that the attentional blink does indeed reflect a loss of information at a postperceptual stage of processing, and provides a demonstration of the modularity of human brain function.

The perceived velocity of visually tracked moving objects may depend on interactions between reflexive and voluntary oculomotor mechanisms. To investigate this hypothesis, subjects were required to compare sequentially the velocity of a standard target with that of a test target moving at one of five velocities. The standard target was viewed against a plain field (no optokinetic stimulation), and the test target was viewed against (1) a plain field, (2) a stationary grating, (3) a grating drifting in the direction of target motion, or (4) a grating drifting against target motion. In one condition, subjects tracked the target; in the other, a stationary point was fixated. The tracking group overestimated velocity when backgrounds drifted against target motion, but underestimated velocity when gratings drifted with target motion. Subjects not required to track experienced no such misestimations. The results are discussed in relation to the interactive mechanisms of the two eye-movement systems.

In a Pavlovian procedure, groups of pigeons were presented with a compound auditory-visual stimulus that terminated with either response-independent electric shock or food. In a subsequent test, the tone CS was dominant in aversive conditioning, reliably eliciting conditioned head raising and prancing. The red light CS was dominant in appetitive conditioning, reliably eliciting pecking. This result was replicated in a second experiment, in which trials were widely spaced. Pour additional groups of pigeons received pairings of the separate element CSs with the USs. Red light, but not tone, was an effective CS in appetitive conditioning, whereas tone, but not red light, was effective in aversive conditioning. There was no discriminative responding in zero-contingency control groups. Several theoretical accounts of these data are discussed.

Human attention research has found that vision controls attention when competing against other sensory modalities, for example, audition, proprioception, taction. Similarly, animal learning experiments have demonstrated visual attentional control when animals are positively motivated but auditory control when aversively motivated. The experiments with animals suggest a way of attenuating visual dominance in humans. Three experiments using human subjects explored the degree of visual versus auditory control exhibited in the presence of different arousal states. In Experiments 1 and 2, an electric shock and a threat of electric shock, respectively, to the subject’s finger resulted in auditory attentional control In Experiment 3, a tactile stimulus resulted in attenuated visual control. The results of these experiments are discussed in relation to the evolutionary advantage conferred by such attentional strategies.