Table 1 ∣.

Technical considerations linked to and cognitive processes examined in performance monitoring in humans and macaques

Item	Humans	Macaques
Technical issues
Acquisition of task rules	Verbal instruction	Non-verbal conditioning
Number of participants	At least 20	Typically 2
Number of sessions or number of trials per individual	Low	High
Motivation	Social reinforcement	Primary reinforcement
Brain geometry	Large, highly folded, idiosyncratic cortex	Small, modestly folded, stereotyped cortex
EEG electrode placement	On scalp	On scalp; on skull beneath scalp and muscles
Typical microelectrode recordings	Brush wire with no layer specificity	Linear electrode arrays allowing layer specificity; square electrode arrays allowing areal sample
Possible causal interventions	Electrical stimulation	Electrical stimulation, pharmacology, lesions, optogenetics
Potential impact of neurological disease and/or medication	Yes	No
Effectors typically studied	Button press with finger	Eye movements, arm movements
Study of individual differences (large samples)	Yes	No
ERP-single neuron correlates	Yes	Yes
Study impact of comorbid neurological disease	Yes	No
Cognitive processes examined
Outcome registration (reward, points)	Yes	Yes
Error monitoring	Yes	Yes
Expertise level	Naive	High
Task switching or multitask comparisons (domain generality)	Yes	No
Response inhibition or conflict monitoring (slowing)	Yes	Yes
Interference or conflict due to reading	Yes	No
Test of awareness of performance	Yes	No
Time estimation	Yes	Yes
Aversive outcomes	No	Yes

ALL factors are considered from the point of view of invasive medial frontal cortex recordings. ‘Yes’ and ‘no’ entries indicate topics that, to date, have or have not been studied routinely in the given species, respectively. EEG, electroencephalography; ERP, event-related potential.