The effect of high approach-motivated positive affect on selective attention under high perceptual load

The study investigates how the motivational intensity of positive affect (high vs. low approach motivation) interacts with perceptual load (high vs. low) to shape selective attention. Grounded in load theory, high load should restrict processing to task-relevant stimuli, whereas low load allows spillover to distractors. Beyond valence/arousal, the motivational dimension of positive affect may narrow (high approach) or broaden (low approach) attentional scope. The research tests whether and when (early vs. late stages) emotional motivation and perceptual load jointly influence attention, using behavioral performance and ERP markers (P1, N1, N2, P3).

Perceptual load theory posits that high load exhausts resources leading to early sensory selection and reduced distractor processing, while low load permits processing of irrelevant stimuli requiring later cognitive control (Lavie, 1995; Lavie et al., 2004, 2014; Lavie, 2010). Emotion influences attention, but most work focused on valence; motivation (intensity and direction) adds a critical dimension (Gable & Harmon-Jones, 2008, 2010a,b). High approach-motivated positive affect narrows attention and enhances distractor suppression compared to low approach-motivated positive affect (Liu et al., 2016). ERP components index stages of processing: early sensory/perceptual P1 (~80–120 ms) and N1 (~140–200 ms) increase with attentional allocation; N2 (200–400 ms) reflects conflict monitoring/suppression; P3 (300–600 ms) reflects resource allocation and is smaller for more demanding conditions (Luck & Kappenman, 2012; Kok, 2001; Kanske & Kotz, 2010). The open question is how top-down emotional motivation and bottom-up perceptual load jointly modulate these stages.

Design: 3 (Affect: high approach-motivated positive [food pictures], low approach-motivated positive [scene pictures], neutral) × 2 (Perceptual load: low vs. high) × 2 (Congruency: congruent vs. incongruent) repeated-measures design. Participants: N=26 right-handed university students in China (17 females; mean age=23, SD=2.15), normal or corrected-to-normal vision; informed consent; approved by Tianjin Normal University ethics committee; compensated. Affect induction and ratings: 30 neutral IAPS pictures; 30 food and 30 scenery images from the internet (1024×768 px). Three per type for practice; 27 per type in the main task. After each block, participants rated 12 emotion adjectives (0–8), including desire (approach motivation), and SAM valence (1–9) and arousal (1–9). Food and scene pictures both induced positive affect; food pictures evoked higher desire than scenes, indexing higher approach motivation. Flanker task stimuli: Central array of six letters around fixation with target (H or S) plus five irrelevant letters (from Q, W, Z, G, T, A, R, B, F, X, L, K). Low load: five identical irrelevant letters; high load: five different irrelevant letters. Peripheral interference letter (H or S) at 6.4° left or right. Congruent: same as target; incongruent: different. Letters were black on gray, 0.7°×1° visual angle, viewed at 80 cm. Procedure: Three blocks (food, scene, neutral) in Latin-square order; each block 216 trials with 50% high vs. low load and 50% congruent vs. incongruent. Trial: fixation 300–500 ms; picture 2000 ms; blank 800–1000 ms; fixation 300–500 ms; Flanker array 500 ms; blank 1000–1200 ms. Target H/S appeared equally at left/right/top/bottom positions. Responses via keypad (counterbalanced mapping). Short breaks provided. EEG/ERP recording: 64-channel Ag/AgCl cap (extended 10–20), Neuroscan. VEOG and HEOG recorded. Ground at midpoint between FPz and Fz. Online reference left mastoid; re-referenced to average of both mastoids. Sampling 500 Hz; bandpass 0.05–40 Hz; impedances <5 kΩ. Blink correction via linear regression. Epochs: −100 to 800 ms relative to flanker onset; baseline −100 to 0 ms. Trials with incorrect responses or exceeding ±75 µV rejected. Mean retained epochs per condition ≈45 (range 37–54). ERP components and windows: P1 (88–108 ms) and N1 (146–174 ms) at PO7/PO8; N2 (240–370 ms) at Fz/FCz/Cz; P3 (400–600 ms) at Cz/CPz/Pz. Statistical analysis: Repeated-measures ANOVAs (Affect × Load × Congruency) with Bonferroni correction; Greenhouse–Geisser correction applied; behavioral RTs and accuracy; ERP mean amplitudes in defined windows.

Affect induction checks: Negative affect ratings near zero; food and scene pictures > neutral on amusement, contentment, happiness, interest, serenity (ps<0.001). Desire showed main effect F(2,50)=222.88, p<0.001, ηp²=0.90; food > scene (p=0.008); both > neutral (ps<0.001). Valence and arousal: neutral < food=scene (ps<0.001; food vs. scene p=1.00 for both). Behavioral RTs: Main effect of perceptual load F(1,25)=117.3, p<0.001, ηp²=0.82 (high load slower: 796.56±107.55 ms vs. low load: 713.29±81.85 ms). Main effect of congruency F(1,25)=24.61, p<0.001, ηp²=0.50 (congruent 748.02±94.20 ms < incongruent 761.83±93.41 ms). No main effect of affect F(2,50)=0.86, p=0.43, ηp²=0.03. Significant Affect×Load interaction F(2,50)=15.36, p<0.001, ηp²=0.38: under high load, high approach-motivated positive affect (781.64±101.66 ms) < low approach-motivated positive affect (810.48±121.28 ms), p<0.01; no notable differences under low load. No other significant interactions. Behavioral accuracy: Main effect of congruency F(1,25)=10.77, p=0.003, ηp²=0.30 (congruent 0.83±0.16 > incongruent 0.82±0.16). No main effects of affect F(2,50)=0.22, p=0.74 or load F(1,25)=1.31, p=0.26; no interactions. ERP P1 (PO7/PO8): No significant main effects or interactions. ERP N1: PO7—main effect of load F(1,25)=11.49, p=0.002, ηp²=0.32 (low load more negative: −8.18±5.09 µV vs. high load −7.76±5.16 µV). PO8—Affect×Load interaction F(2,50)=3.36, p=0.04, ηp²=0.12: under high load, low approach-motivated positive affect more negative (−9.22±5.47 µV) than high approach-motivated positive affect (−8.42±5.06 µV), p=0.039. ERP N2 (Fz/FCz/Cz): Main effect of affect F(2,50)=5.62, p=0.006, ηp²=0.18: high approach-motivated positive affect (−2.72±2.88 µV) more negative than low approach-motivated positive affect (−1.72±2.51 µV), p=0.011; trend vs. neutral (−2.02±2.72 µV), p=0.075. Main effect of load F(1,25)=9.16, p=0.006, ηp²=0.27: high load more negative (−2.48±2.54 µV) than low load (−1.82±2.68 µV). Congruency ns; no interactions. ERP P3 (Cz/CPz/Pz): Main effect of affect F(2,50)=4.49, p=0.017, ηp²=0.15: neutral (6.02±3.85 µV) > high approach-motivated positive affect (4.99±3.83 µV), p=0.033; low approach-motivated positive affect (5.99±4.05 µV) trended > high approach-motivated positive affect, p=0.066. Main effect of load F(1,25)=69.63, p<0.001, ηp²=0.74: low load (6.83±4.07 µV) > high load (4.50±3.52 µV). Main effect of congruency F(1,25)=4.81, p=0.038, ηp²=0.16: congruent (5.87±3.81 µV) > incongruent (5.46±3.73 µV). No significant interactions.

Findings show that approach-motivational intensity modulates selective attention particularly under high perceptual load. Behaviorally, high approach-motivated positive affect shortened RTs relative to low approach-motivated positive affect when the task was demanding. ERPs suggest mechanisms across stages: early, low approach-motivated positive affect under high load elicited a larger N1 over parieto-occipital cortex, indicating broader attentional allocation and more extensive discrimination of stimuli, including distractors, consistent with broadened attention. Late, high approach-motivated positive affect increased frontal N2 (greater conflict monitoring/attentional control) and reduced parietal P3 (reflecting higher control demands/resource engagement), supporting enhanced cognitive control and distractor inhibition. Together, motivationally intense positive affect can focus attention and bolster control to facilitate performance in high-load contexts, whereas low approach-motivated positive affect broadens attention and can hinder efficiency.

The study demonstrates that high approach-motivated positive affect facilitates, and low approach-motivated positive affect hinders, performance on a perceptual-load Flanker task, with effects most evident under high load. ERP evidence localizes these influences to both early perceptual discrimination (N1) and later control/monitoring stages (N2, P3). These results underscore the top-down impact of emotional motivation on selective attention and have implications for optimizing performance in demanding work and learning settings.