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

Area of Science:

• Cognitive Psychology
• Human Factors
• Neuroscience

Background:

• The Simon effect is a cognitive phenomenon where response performance is influenced by the spatial location of a stimulus, even when location is irrelevant to the task.
• The attention-shift hypothesis proposes that the Simon effect arises from the spatial orienting of attention.
• Previous research has explored various factors influencing the Simon effect, but the precise role of attention shifts remains debated.

Purpose of the Study:

• To investigate the attention-shift hypothesis of the Simon effect.
• To analyze how repeating stimulus features (color or location) affects the Simon effect across different response-stimulus intervals (RSI).
• To explore the underlying mechanisms, including feature binding, that may explain the Simon effect and response blocking.

Main Methods:

• Four serial reaction time tasks were conducted, manipulating stimulus location repetition and response-stimulus intervals (RSI).
• Experiments varied RSI duration (short vs. long) to control for attentional engagement at the fixation cross.
• Stimulus presentation timing and location were manipulated to hinder or facilitate attention disengagement and shifts.

Main Results:

• No Simon effect was observed when stimulus location was repeated in short RSI tasks, supporting the attention-shift hypothesis.
• A Simon effect was present for both location repetitions and alternations in long RSI tasks.
• The Simon effect was reduced for location repetitions when attention disengagement was hindered (stimulus presented after response).
• Faster responses occurred when attention shifts to a central stimulus aligned with the response location.
• Feature binding into object files was proposed as an alternative explanation for response blocking.

Conclusions:

• The findings provide evidence for the attention-shift hypothesis, particularly concerning the role of attention in the Simon effect.
• Stimulus-response compatibility and attentional processes interact, with RSI and stimulus presentation timing being critical factors.
• Feature binding offers a potential framework for understanding complex interactions between stimulus features and response selection, including the blocking of automatic priming.