The effects of relative intensity of cue and marker on marked trace conditioning in pigeons

Pigeons were trained on trace conditioning procedures (autoshaping) in which a keylight conditioned stimulus (CS) was presented for 5 sec and followed after a 10-sec temporal gap by food. In Experiment 1, acquisition of conditioned responding to the CS was facilitated when it was immediately followed by a brief stimulus, but only when the brief stimulus was of greater intensity than the trace CS. In Experiment 2, this facilitation effect was found when a more intense brief stimulus followed the trace CS immediately, but not when it was delayed. In both experiments, responding to the target CS was compared within-subjects to that to a control CS, which eliminated factors such as second-order conditioning as an explanation for the facilitation effects. Together, the results of Experiments 1 and 2 suggest that a brief stimulus may mark immediately preceding events in memory and thus facilitate their association with delayed reinforcement only if the brief stimulus is relatively more intense, and thus more salient, than the target events. In Experiment 3, we found substantial generalization of this facilitation effect from the marked CS to the control CS and conclude that the results of Experiments 1 and 2 may underestimate the magnitude of these marking effects.     

What Can Spatial Deficits Teach Us About Feature Binding and Spatial Maps?

The “binding problem” is discussed with reference to feature integration and visual search. Neuropsychological and neurophysiological findings support the existence of multiple visual areas within the primate cortex that respond to primary features of objects and spatial locations. Evidence from studies with hemineglect and Balint's syndrome supports the role of spatial attention in feature integration and demonstrates the necessity for an intact, explicitspatial representation. Some implicit spatial maps remain intact but are not sufficient to support the perception of properly bound features. The evidence suggests strong interactions between parietal spatial representations and temporal feature representations in feature integration.     

Transitivity for height versus speed: To what extent do the under-7s really have a transitive capacity?

Transitive inference underpins many human reasoning competencies. The dominant task (the “extensive training paradigm”) employs many items and large amounts of training, instilling an ordered series in the reasoner's mind. But findings from an alternative “three-term paradigm” suggest transitivity is not present until 7 + years. Interestingly, a second alternative paradigm (the “spatial task”), using simultaneously displayed height relationships to form premise pairs, can uphold the 4-year estimate. However, this paradigm risks cueing children and hence is problematic. We investigated whether a height-task variant might correspond to a more ecologically valid three-term task. A total of 222 4–6-year-olds either completed a modified height task, including an increased familiarisation phase, or a computer-animated task about cartoon characters running a race in pairs. Findings confirmed that both tasks were functionally identical. Crucially, 4-year-olds were at chance on both, whereas 6-year-olds performed competently. These findings contrast with estimates from all three paradigms considered. A theoretical evaluation of our tasks and procedures against previous ones, leads us to two conclusions. First, our estimate slightly amends the 7-year estimate offered by the three-term paradigm, with the difference explained in terms of its greater relevance to child experiences. Second, our estimate can coexist alongside the 4-year estimate from the extensive training paradigm. This is because, applying a recently developed “dual-process” conception of reasoning, anticipates that extensive training benefits a species-general associative system, while the spatial paradigm and three-term paradigm can potentially index a genuinely deductive system, which has always been the target of transitive research.