Social, cognitive, and physiological aspects of humour perception from 4 to 8 months: Two longitudinal studies.

Infants laugh by 4 months, but whether they understand humour based on social or cognitive factors is unclear. We conducted two longitudinal studies of 4-, 6-, and 8-month-olds (N = 60), and 5-, 6-, and 7-month-olds (N = 53) to pinpoint the onset of independent humour perception and determine when social and cognitive factors are most salient. Infants were shown six events in randomized repeated-measures designs: two ordinary events and two absurd iterations of those events, with parents' affect manipulated (laugh or neutral) during the latter. Four-month-olds did not smile/laugh more at absurd events, but exhibited a significant heart rate deceleration. Five-month-olds independently appraised absurd events as humorous, smiling/laughing despite their parents' neutrality. Parent laughter did not influence infants of any age to smile more, but captured 4-month-olds' attention. Results suggest that 4-month-olds laugh in response to social cues, while 5-month-olds' can laugh in response to cognitive features. Statement of contribution What is already known on this subject? By 6 months, infants can independently appraise absurd events as humorous, but it is not known whether younger infants can. What does this study add? This study replicated the finding on younger infants, showing that 5-month-olds are similarly capable of independent humour appraisal. These studies also found that although 4-month-olds do not respond to absurd events with positive affect, they do exhibit a heart rate decrease that is unrelated to looking. These studies help delineate when social and cognitive factors contribute to infant humour perception.

Individual differences in motion-induced blindness: The effects of mask coherence and depth ordering.

Motion-induced blindness (MIB; Bonneh, Cooperman, & Sagi, 2001) is a visual phenomenon in which salient, stationary high-contrast targets are perceived to disappear and reappear when viewed within a moving background mask. The present study examined the effects of depth ordering (three levels) and mask motion coherence (0%, 50%, and 100% coherence of the mask elements), as well as the interaction effects between these two variables, especially taking note of between-subject variation. It is clear that individuals experience different amounts of MIB, indexed using average, cumulative, and normalized measures. Other differences are exhibited in how depth order and levels of mask coherence affect individuals' perception of MIB. This study was able to partially replicate the depth ordering effects exhibited by Graf, Adams, and Lages (2002); however, we were unable to replicate the effects of mask coherence reported by Wells, Leber, and Sparrow (2011), and possible reasons are explored, including the possible role of adaptation. No significant interaction effect was found between depth order and coherence, suggesting these processes act independently of one another. Implications for between-subject variability are discussed. A single underlying parameter accounting for individual differences among observers was not identified, suggesting that normative models of MIB may not be practical.

Laughing matters: Infant humor in the context of parental affect.

Smiling and laughing appear very early during the first year of life, but little is known about how infants come to appraise a stimulus as humorous. This short-term longitudinal study explored infant humor perception from 5 to 7 months of age as a function of parental affect during an absurd event. Using a within-participants design, parents alternated smiling/laughing with emotional neutrality while acting absurdly toward their infants. Group comparisons showed that infants (N = 37) at all ages smiled at the event regardless of parental affect but did so significantly longer at 5 and 6 months, and more often and sooner at 7 months, when parents provided humor cues. Similarly, sequential analyses revealed that after gazing at the event, 7-month-olds were more likely to smile at it only when parents provided humor cues and were comparatively more likely to look away when parents were neutral. Thus, starting at 5 months of age, parental affect influenced infants' affect toward an absurd event, an effect that was magnified at 7 months. These results are discussed in the context of emotional contagion, regulation, and the emergence of social referencing.

Social looking, social referencing and humor perception in 6- and-12-month-old infants.

Social referencing refers to infants' use of caregivers as emotional referents in ambiguous situations (Walden, 1993). Studies of social referencing typically require ambulation, thereby over-looking younger, non-ambulatory infants (i.e., ≤8-months) and resulting in a widespread assumption that young infants do not employ this strategy. Using a novel approach that does not require mobility, we found that when parents provided unsolicited affective cues during an ambiguous-absurd (i.e., humorous) event, 6-month-olds employ one component of social referencing, social looking Additionally, 6-month-olds who did not laugh at the event were significantly more likely to look toward parents than their counterparts who found the event funny. Sequential analyses revealed that, following a reference to a smiling parent, 6-month olds were more likely to smile at the parent, but by 12 months were more likely to smile at the event suggesting that older infants are influenced by parental affect in humorous situations. The developmental implications of these findings are discussed, as well as the usefulness of studying humor for understanding important developmental phenomena.

The role of mask coherence in motion-induced blindness.

Motion-induced blindness (MIB) is the perceived disappearance of a salient target when surrounded by a moving mask. Much research has focused on the role of target characteristics on perceived disappearance by a coherently moving mask. However, we asked a different question: mainly, are there certain characteristics about the mask that can impact disappearance? To address this, we behaviorally tested whether MIB is enhanced or reduced by the property of common fate. In experiments 1, 2, and 3, we systematically manipulated the motion coherence of the mask and measured the amount of target disappearance. Results showed that, as mask coherence increased, perceived target disappearance decreased. This pattern was unaffected by the lifetime of the moving dots, the dot density of the motion stimulus, or the target eccentricity. In experiment 4, we investigated whether the number of motion directions contained in an incoherent mask could account for our findings. Using masks containing 1, 3, and 5 motion directions, we found that disappearance did not increase proportionally to the number of motion directions. We discuss our findings in line with current proposed mechanisms of MIB.