Table 2.
Comparisons between event-related potential (ERP) studies based on components, stimuli, and locations. All ERP components consist of two components: type of polarity, and number of milliseconds after the onset of the stimulus. For example, a positive-going peak, which is the first measurable peak in the ERP waveform (occurring about 100 ms after the stimulus onset), is called P100 or P1.
| Component | Stimulus | Summary | Location | Ref. |
|---|---|---|---|---|
| P1, N1, P2, P3 | Mood adjectives (32 stimuli over 6 presentations). Subjects = 17. Duration: subliminal = 1 ms, supraliminal = 40 ms. | The study demonstrated that ERPs are sensitive to affective valences, whether consciously or unconsciously. | F3, F4, P3, P4, Cz, Pz, Oz | [92] |
| P1 | Images of happy or fearful and surprised facial expressions (n = 140). Subjects = 17. Duration: primes (fearful or happy) = 30 ms, targets (surprised) = 800 ms. | Larger occipital P1 components were found with fearful rather than happy expressions. | A source analysis implicated the bilateral extrastriate cortex. | [116] |
| N1, P2 | Threatening and neutral words were used as primes for groups with high and low social anxiety. The targets were images of neutral and angry facial expressions (n = 16). Subjects = 24. Duration: primes = 200 ms, targets = 500 ms. | The high social anxiety group showed attention bias after viewing the neutral primes but not the threatening primes, indicating suppression of the attention bias. The low social anxiety group demonstrated opposite effects. | O1/O2 | [117] |
| N2, P3 | Go/no-go task with subliminal primes (14 blocks of 72 arrow shapes; trials = 1008). Subjects = 21. Duration: primes = 16 ms, targets = 100 ms. | Inhibition-related ERPs were modulated as a function of prime congruency. The inhibition of impending motor responses can be initiated by unconscious stimuli. | The primes influenced frontal inhibitory control mechanisms. | [118] |
| P2, P3 | Earthquake-(un)related words (12 of each category). Subjects = 24. Duration: primes = 17 ms, targets = 1500 ms. | More positive ERP deflections in related words than unrelated words. | P2: Posterior cingulate cortex; P300: parahippocampal gyrus | [118,119] |
| P3 | Names of acquaintances in a lie detection protocol (5 known names, 4 unknown names). Subjects = 14. Duration: primes = 17 ms, targets = 150 ms. | Subliminal primes modulate ERPs when the task involves lying. | Fz, Cz, Pz, Oz | [120] |
| P3 | Logic-based learning paradigms (3 magic squares of odd order). Subjects = 46. Duration: primes = 33.33 ms, targets = unknown. | Subliminal “cues” increased learner performances. | Not stated | [121] |
| N1.9, P1.9, N4 | Repeated images preceded by masked image primes (n = 80). Subjects = 16. Duration: primes = 50 ms, targets = 300 ms. | Reduced amplitudes in N/P190 that may reflect early processing of object-specific representations. Changes in N400 reflect more domain-general sematic processing. | Posterior/anterior (locations not specified) | [122] |
| N2.5, N4 | Animal names in streams of words with masked primes (numbers unknown). Subjects = 24. Duration: primes = 40 ms, targets = 300 ms. | N250 reflects processing at the level of forms, while N400 reflects processing at the level of meaning. | Parietal (CP1) | [123] |
| P2, N4 | Concrete and abstract emotional words (720 German nouns). Subjects = 30. | Concreteness affected N400 and LPC. | FC3, FC4 | [124] |
| N4 | Action sentences (156 Spanish sentences: 104 related to hand actions, 52 neutral sentences). | N400 distinguished between compatible and incompatible primes and was more negative for incompatible primes. | Cz | [125] |
| P6, N9 | Visual stimuli (3 ethnicities: white/Caucasian, East-Asian, and Afro-Caribbean) and olfactory stimuli (3 odor conditions: pleasant, unpleasant and a neutral control). Subjects = 20. Duration: primes = 3 s, targets = 300 ms. | Significant effects of odor were observed at 600 and 900 ms after face-onset | Left and right lateral frontal-temporal electrodes | [45] |