Oddball Paradigms

 [Concepts in Sensorimotor Research]

Oddball trials, also known as oddball tasks or oddball paradigms, are a type of research experimental design. In oddball trials, a sequence of stimuli is presented to participants, and their task is to detect and respond to specific target stimuli embedded within a stream of more frequent, standard stimuli. The oddball paradigm has been widely used in autism research to investigate sensory processing differences, attentional issues, and cognitive control.

The oddball paradigm typically consists of two types of stimuli:

• Standard Stimuli: These are the most common stimuli presented in the sequence and serve as the baseline / control stimuli, occurring with higher frequency. Participants are generally instructed to ignore standard stimuli and withhold any response to them
• Target Stimuli: These are the less frequent or "oddball" stimuli that differ in some way from the standard stimuli. Participants are instructed to actively detect and respond to these target stimuli. The target stimuli can be defined by various characteristics, such as a different color, shape, sound, or any other perceptual feature.

The purpose of oddball trials is to investigate how the brain processes and detects rare or deviant stimuli amidst a background of more common stimuli. By manipulating the frequency and characteristics of the target and standard stimuli, researchers can examine various aspects of cognitive processing, including

• Attention: how participants allocate and sustain their attention to detect infrequent target stimuli. It allows researchers to explore the mechanisms of selective attention, attentional capture, and the ability to filter out irrelevant information.
• Perception & perceptual processing: how the brain discriminates between different stimuli; how the brain detects and discriminates deviant stimuli based on sensory features, and how it forms representations and expectations about the environment
• Memory and Cognitive Control: Participants may be required to remember the occurrence or characteristics of the target stimuli and maintain this information for subsequent recall or recognition. Also sheds light on cognitive control processes, such as response inhibition and response selection when distinguishing between standard and target stimuli.

During an oddball task, researchers typically measure various physiological and behavioral responses, such as reaction times, accuracy rates, ERPs (via EEG) or fMRI (to examine neural activity patterns).