Synaesthesia: the existing state of affairs.

In synaesthesia one type of stimulation evokes the sensation of another, such as when hearing a sound produces photisms--that is, mental percepts of colours. In the past, the idiosyncrasy of this phenomenon, as well as the natural mistrust of scientists towards the subjective, consigned synaesthesia to the periphery of scientific interest. However, the landscape has changed radically in the last two decades. The labour of many researchers, inside as well as outside of cognitive neuroscience, has transformed synaesthesia into a scientific reality whose existence can be demonstrated and studied empirically. The present paper summarizes and reflects on our current knowledge concerning synaesthesia in all its aspects (cognition, behaviour, neurology, genetics, and demographics).

The nature of residual cost in regular switch response factors.

Two experiments are presented that compare the residual cost found when switching from one task to another under predictable conditions. The aim of the study was to explore the roles played by the stimulus, the response, or both in the process of the mental set reconfiguration necessary to switch between two tasks. The experiments tested [Rogers, R. D., & Monsell, S. (1995). Cost of a predictable switch between simple cognitive tasks. Journal of Experimental Psychology: General, 124, 207-231] stimulus-cued-completion hypothesis and [Schuch, S., & Koch, I. (2003). The role of response selection for inhibition of task sets in task shifting. Journal of Experimental Psychology: Human Perception and Performance, 29, 92-105] hypothesis of response selection as the key factor in the nature of switch cost. In the first experiment, two conditions were created that varied in terms of a Go/No-Go signal: The Go trials were a replication of [Tornay, F. J., & Milán, E. G. (2001). A more complete task-set reconfiguration in random than in predictable task switch. The Quarterly Journal of Experimental Psychology, 54A, 785-803 Experiment 3]; The No-Go trials were identical to the first condition, except that participants did not execute a response in the trial n-1 (Schuch & Koch, 2003). In addition, the percentage of Go and No-Go trials was manipulated. The results showed that the cost was significant only in the high Go signal-frequency case (Experiment 2), with an abrupt offset in Go trials and a gradual offset in No-Go trials. Based on the results of these experiments, it was concluded that the crucial factor to complete a mental set reconfiguration is response-related and not stimulus-related.

The response-cued completion hypothesis and the nature of residual cost in regular switch.

Three experiments are presented that compare the residual cost found when shifting from one task to another under different extra-response conditions, to test whether the response is the main factor to complete mental set reconfiguration. We investigated whether residual costs can be eliminated if participants carry out a response prior to completing switch trials. In all experiments, participants were required to press an extra key during the inter-trial interval (ITI) to proceed. In experiment 1, this extra response consisted of pressing the space bar. In experiment 2, the response consisted of pressing one of the two possible keys that belonged to the alternating tasks response set. In experiment 3, the interpolated response involved pressing one of the two possible keys, not belonging to the response set of the alternating tasks. We found no residual cost in the second or the third experiments. To explain the nature of residual cost we discuss the data in the context of a response cued completion hypothesis.