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Prelinguistic human infants and great apes show different communicative strategies in a triadic request situation

View Article: PubMed Central - PubMed

ABSTRACT

In the present research, we investigate the communicative strategies of 20 month old human infants and great apes when requesting rewards from a human experimenter. Infants and apes both adapted their signals to the attentional state of the experimenter as well as to the location of the reward. Yet, while infants frequently positioned themselves in front of the experimenter and pointed towards a distant reward, apes either remained in the experimenter’s line of sight and pointed towards him or moved out of sight and pointed towards the reward. Further, when pointing towards a reward that was placed at a distance from the experimenter, only the infants, and not the apes, took the experimenter’s attentional state into account. These results demonstrate that prelinguistic human infants and nonhuman apes use different means when guiding others’ attention to a location; indicating that differing cognitive mechanisms may underlie their pointing gestures.

No MeSH data available.


Related in: MedlinePlus

Box plot of the average number of visual gestures per trial that human infants (upper row) and apes (lower row) produced on the experimenter’s side (EXP: left column) and the other side (OTH: right column) across the factors orientation (Towards: two leftmost boxes in each plot, Away: two rightmost boxes in each plot) and location (red: experimenter and reward are on the same side, blue: experimenter and reward are on different sides) resulting in the four experimental conditions towards-same (TS), towards-different (TD), away-same (AS) and away-different (AD); M: condition mean value, the middle line of each box represent population median values (different from the M above each box); lower and upper hinges display first and third quartiles, respectively; whiskers extend up to 1.5 x interquartile range, small circles represent individual data points.
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pone.0175227.g003: Box plot of the average number of visual gestures per trial that human infants (upper row) and apes (lower row) produced on the experimenter’s side (EXP: left column) and the other side (OTH: right column) across the factors orientation (Towards: two leftmost boxes in each plot, Away: two rightmost boxes in each plot) and location (red: experimenter and reward are on the same side, blue: experimenter and reward are on different sides) resulting in the four experimental conditions towards-same (TS), towards-different (TD), away-same (AS) and away-different (AD); M: condition mean value, the middle line of each box represent population median values (different from the M above each box); lower and upper hinges display first and third quartiles, respectively; whiskers extend up to 1.5 x interquartile range, small circles represent individual data points.

Mentions: Across sides, infants produced a higher number of visual gestures at the experimenter’s side in three out of four conditions (TS: T+ = 105.0, N = 14, p < .001; TD: T+ = 53.0, N = 10, p = .008; AS: T+ = 41.0, N = 9, p = .027; see Fig 3). In the AD condition they showed no preference for either side (T+ = 35.0, N = 11, p > .922). Apes exhibited a preference to produce visual gestures in proximity to the reward, that is, they visually gestured more frequently on the experimenter’s side when the reward was located on the same side (TS: T+ = 528.0, N = 32, p < .001; AS: T+ = 458.0, N = 30, p < .001), whereas they produced more visual gestures on the other side when the experimenter and the reward were located on different sides (TD: T+ = 363.0, N = 31, p = .023; AD: T+ = 383.0, N = 28, p < .001). If the analyses were restricted to the two Pan species, the difference across sides in the TD condition turned into a trend (TD: T+ = 193.5, N = 23, p = .093).


Prelinguistic human infants and great apes show different communicative strategies in a triadic request situation
Box plot of the average number of visual gestures per trial that human infants (upper row) and apes (lower row) produced on the experimenter’s side (EXP: left column) and the other side (OTH: right column) across the factors orientation (Towards: two leftmost boxes in each plot, Away: two rightmost boxes in each plot) and location (red: experimenter and reward are on the same side, blue: experimenter and reward are on different sides) resulting in the four experimental conditions towards-same (TS), towards-different (TD), away-same (AS) and away-different (AD); M: condition mean value, the middle line of each box represent population median values (different from the M above each box); lower and upper hinges display first and third quartiles, respectively; whiskers extend up to 1.5 x interquartile range, small circles represent individual data points.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5383261&req=5

pone.0175227.g003: Box plot of the average number of visual gestures per trial that human infants (upper row) and apes (lower row) produced on the experimenter’s side (EXP: left column) and the other side (OTH: right column) across the factors orientation (Towards: two leftmost boxes in each plot, Away: two rightmost boxes in each plot) and location (red: experimenter and reward are on the same side, blue: experimenter and reward are on different sides) resulting in the four experimental conditions towards-same (TS), towards-different (TD), away-same (AS) and away-different (AD); M: condition mean value, the middle line of each box represent population median values (different from the M above each box); lower and upper hinges display first and third quartiles, respectively; whiskers extend up to 1.5 x interquartile range, small circles represent individual data points.
Mentions: Across sides, infants produced a higher number of visual gestures at the experimenter’s side in three out of four conditions (TS: T+ = 105.0, N = 14, p < .001; TD: T+ = 53.0, N = 10, p = .008; AS: T+ = 41.0, N = 9, p = .027; see Fig 3). In the AD condition they showed no preference for either side (T+ = 35.0, N = 11, p > .922). Apes exhibited a preference to produce visual gestures in proximity to the reward, that is, they visually gestured more frequently on the experimenter’s side when the reward was located on the same side (TS: T+ = 528.0, N = 32, p < .001; AS: T+ = 458.0, N = 30, p < .001), whereas they produced more visual gestures on the other side when the experimenter and the reward were located on different sides (TD: T+ = 363.0, N = 31, p = .023; AD: T+ = 383.0, N = 28, p < .001). If the analyses were restricted to the two Pan species, the difference across sides in the TD condition turned into a trend (TD: T+ = 193.5, N = 23, p = .093).

View Article: PubMed Central - PubMed

ABSTRACT

In the present research, we investigate the communicative strategies of 20 month old human infants and great apes when requesting rewards from a human experimenter. Infants and apes both adapted their signals to the attentional state of the experimenter as well as to the location of the reward. Yet, while infants frequently positioned themselves in front of the experimenter and pointed towards a distant reward, apes either remained in the experimenter&rsquo;s line of sight and pointed towards him or moved out of sight and pointed towards the reward. Further, when pointing towards a reward that was placed at a distance from the experimenter, only the infants, and not the apes, took the experimenter&rsquo;s attentional state into account. These results demonstrate that prelinguistic human infants and nonhuman apes use different means when guiding others&rsquo; attention to a location; indicating that differing cognitive mechanisms may underlie their pointing gestures.

No MeSH data available.


Related in: MedlinePlus