Timing the events of directional cueing

Temporal preparation in adults with autistic spectrum disorder: The variable foreperiod effect

Research suggested the possibility that temporal cognition may be different in autistic spectrum disorder (ASD). Although there are some empirical studies examining timing ability in these individuals, to our knowledge, no one directly assessed the ability to predict when an event will occur. Here, we report a study on implicit temporal preparation in individuals with ASD as indexed by the variable foreperiod (FP) effect. We compared a group of adult ASD participants to a group of typically-developed (TD) controls, for their respective abilities to utilize implicit temporal information in a simple detection task with three different preparatory intervals (FP, short, middle and long). Participants were given a warning tone to signal an imminent stimulus, and asked to press a key as quickly as they could upon detection of the stimulus. Both groups were able to use implicit temporal information, as revealed by both the variable-FP effect (i.e., faster response for targets appearing after a long FP) and asymmetric sequential effects (i.e., slower response in short-FP trials following a previous long-FP trial). The TD group exhibited a faster response in a long-FP trial that was preceded by short-FP one, whereas the ASD group did not, as reflected in their higher percentage of response omissions for a target that appeared later than in the previous trial. The reduced ability of ASD participants to modulate their responses under these conditions might reflect a difficulty in time-based monitoring of stimulus occurrence. LAY SUMMARY: Time-processing may be different in autistic spectrum disorder (ASD). This study addressed the ability to anticipate a relevant stimulus's onset according to predictable interstimulus intervals comparing adults with ASD and typically developed controls. We found that ASD participants did not benefit from temporal preparation when stimulus appeared later than previously attended. This suggests a reduced ability in detecting implicit temporal regularities between events.

Local probability effects of repeating irrelevant attributes

We present two experiments in which participants classify stimuli having two potentially conflicting attributes, one of which is response-relevant whereas the other ("irrelevant") attribute is logically and statistically independent of the response. We introduce a novel design not used with filtering tasks before in which the main factor is the local (i.e., one-step) transition probability π (= 0.25, 0.50, 0.75) that the irrelevant attribute is repeated from one trial to the next. Experiment 1 involved a visual Simon task in which the color of the stimulus is relevant and its location is irrelevant. Experiment 2 used a semantic classification task in which the parity of a digit presented is relevant and its numerical magnitude is irrelevant. The results of both experiments demonstrate that participants in the π = 0.75 group responded faster when the irrelevant attribute is in fact repeated rather than alternated; in contrast, participants in the π = 0.25 group responded faster (Experiment 1) or equally fast (Experiment 2) when the irrelevant attribute is alternated rather than repeated. These expectancy-related effects cannot be attributed to spurious design contingencies as the irrelevant attribute was independent of the relevant attribute (and thus of the response), of the congruency status, and also of their alternation/repetition. One interpretation of our findings is that information about the irrelevant attribute in the previous trial is used much as an informative central precue, so that participants can prepare early processing stages in the current trial, with the corresponding benefits and costs typical of standard cueing studies.