Non-corresponding Trials Research Articles

Sequential analysis of a Simon task--evidence for an attention-shift account.

We investigated the attention-shift hypothesis of the Simon effect by analysing the effect of repeating relevant colour or irrelevant location of the stimulus in four serial reaction time tasks. In Experiment 1 with short response-stimulus intervals (RSI), we assume that there is no time to engage attention at the fixation cross before the onset of a new stimulus. In agreement with the hypothesis, Experiment 1 reveals no Simon effect when the stimulus location is repeated. In Experiment 2 with long RSI, we observe a Simon effect for location repetitions and alternations. In Experiment 3 with long RSI, we hinder the disengagement of attention by displaying the stimulus after response execution. As expected, the Simon effect is reduced for location repetitions. In Experiment 4 with stimuli additionally presented at the fixation cross, responses are faster if the attention shift towards the centrally presented stimulus corresponds with the location of the required response. Additionally, we argue that binding of the stimulus features into an object or event file better explains the so-called blocking of the automatic response-priming route after a noncorresponding trial.

An or analysis of the tendency to react toward the stimulus source

Reactions are considerably slower when stimuli and responses are in opposite directions (non-corresponding trials) than when they are in the same direction (corresponding trials). It is said that a natural tendency to react toward the source of stimulation underlies this difference. The present study investigated the hypothesis that this response tendency is a behavioral manifestation of the more basic orienting reflex (OR). Subjects performed a visual choice reaction task in which a 5 dB(A) increase in background noise at either left or right ear accompanied the visual stimulus. The results showed a 32 msec difference between corresponding and non-corresponding trials which did not decrease with repeated presentations. These findings argue against an OR interpretation of the response tendency. While an OR is sensitive to intensity manipulations and repeated stimulation, the response tendency is not sensitive to stimulus intensity and resists habituation. The results are discussed in the context of recent interpretations of the interference effect elicited by location cues associated with auditory accessories.

Effect of irrelevant information on the processing of relevant information: facilitation and/or interference? The influence of experimental design.

Previous studies have provided conflicting evidence concerning the question of whether irrelevant information can facilitate the processing of relevant information in a choice reaction time task. Results of the present study demonstrated that indications of facilitation and/or interference were dependent on the context in which baseline trials were administered. Three groups of 24 subjects pressed a left-.or right-hand key in response to the onset of an X or 0 that was accompanied by a monaural or binaural tone. The monaural toneprovided an irrelevant directional cue since, oia some trials, it was ipsilateral to the correct response (corresponding trials), while, on other trials, it was contralateral Inoncorrasponding trials). When binaural (baseline) trials were presented in the same block as the monaural trials, data suggested that the directional cue produced both facilitation and interference. However, when baseline trials were presented in one block, and corresponding and noncorresponding trials were mixed together in another block, data suggested an interference effect only. The difference was attributed to differences in the degree of stimulus uncertainty within a block of trials.

Effects of stimulus-response correspondence and verbal expectancy on choice reaction time.

The effects of S-R correspondence, verbal prediction, and stimulus discriminability were examined in a discrete, two-choice reaction-time task. Correctness of prediction and S-R correspondence were significant main effects. In addition, responses were significantly faster for correct predictions on noncorresponding trials than for incorrect predictions on corresponding trials. This latter finding indicates that an expectancy mechanism can partially offset the negative effect of spatial S-R noncorrespondence on absolute magnitude of choice reaction time.

Effect of locus of warning tone on auditory choice reaction time

Forty Ss pressed a left- or right-hand key depending on the ear in which they heard a 500-Hz stimulus tone. Half of the Ss were instructed to press the key on the same side as the ear stimulated (corresponding condition), while the other half pressed the key on the opposite side (noncorresponding condition). A 200-Hz warning tone preceded the stimulus tone by either 200 or 400 msec. The warning tone was presented to the left ear, the right ear, or to both ears in a predetermined random sequence. The locus of the warning tone affected RT on noncorresponding trials but not on corresponding trials. The effect consisted of a significant slowing of information processing on trials where the warning tone was contralateral to the response. Results were explained in terms of an initial tendency to respond toward the source of the warning tone.