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Counting distance: Effects of egocentric distance on numerical perception

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ABSTRACT

Numerical value is long known to be associated with a variety of magnitude representations, such as size, time and space. The present study focused on the interactive relations of numerical magnitude with a spatial factor which is dominant in everyday vision and is often overlooked, namely, egocentric distance, or depth. We hypothesized that digits denoting large magnitudes are associated with large perceived distances, and vice versa. While the relations of numerical value and size have been long documented, effects of egocentric distance on numeral perception have been scarcely investigated, presumably due to the difficulty to disentangle size and depth factors within three-dimensional visual displays. The current study aimed to assess the potential linkage between egocentric distance and number magnitude, while neutralizing any perceived and/or physical size parameters of target digits. In Experiment 1, participants conducted a numeral size-classification task (‘bigger or smaller than 5’), to which they responded with a near-to-body or a far-from-body key. Results revealed shorter responses for small than for large numbers when responded with a key positioned close to the body, and for large than small numbers when responded with a key positioned far from the body (regardless of hand-key mapping). Experiment 2 used verbal stimuli denoting near/remote concepts as irrelevant primes to target digits, further demonstrating a priming effect of conceived distance on numerical value processing. Collectively, our results suggest that distance magnitudes are associatively linked to numerical magnitudes and may affect digit processing independently of the effects of visual size.

No MeSH data available.


Related in: MedlinePlus

Reaction times in Experiment 1, as a function of response hand and numerical value, within each of the hand-position groups.In one group, the right hand was positioned on the far key and the left hand was positioned on the close key (a), while in the other group response keys were flipped (b). Standard errors are computed for the difference score (between big and small numerical values) [19], within each of the response hand conditions.
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pone.0174772.g002: Reaction times in Experiment 1, as a function of response hand and numerical value, within each of the hand-position groups.In one group, the right hand was positioned on the far key and the left hand was positioned on the close key (a), while in the other group response keys were flipped (b). Standard errors are computed for the difference score (between big and small numerical values) [19], within each of the response hand conditions.

Mentions: An Anova conducted on the RT data indeed revealed a statistically significant three-way interaction, F(1,30) = 7.75, p<0.01, η2p = .21. To better understand the nature of this interaction we further conducted a two-way Anova within each of the hand-position groups. Fig 2 presents participants’ RTs as a function of hand (Right/Left) and numerical value (Big/Small), within each of the hand-position groups (N = 16). As can be clearly seen, when the right hand was positioned on the far key and the left hand was positioned on the close key (Fig 2A), a typical SNARC effect was obtained, F(1,15) = 14.47, p<0.005, η2p = 0.49, stemming from shorter RTs to big than to small numbers responded with the right hand, and to small than big numbers responded with the left hand (t(15) = 2.86, 2.5, respectively; p<0.05 using Tukey post-hoc criterion). As explained above, this Left-Right spatial-numerical mapping was confounded with a Near-Far mapping. However, when the right hand was positioned on the close key and the left hand was positioned on the far key (Fig 2B), the results pattern flipped. Rather than obtaining the typical Left-Right SNARC effect, the statistically significant interaction supported a Near-Far spatial-numerical mapping, F(1,15) = 6.56, p<0.03, η2p = 0.30. That is, responses were faster to big than to small numbers when responded with the left (far) hand, and were faster to small than to big numbers when responded with the right (close) hand (t(15) = 2.86, 2.5, respectively; p<0.05 using Tukey post-hoc criterion). Taken together, these findings strongly support a Near-Far spatial-numerical response mapping, which dominated a Left-Right mapping typically observed when participants are requested to respond to a central digit with left and right responses. It appears that when using a close-to-far response axis, rather than a left-to-right one, the latter axis becomes irrelevant to task requirements and is thus ineffective in its influence on number magnitude representation.


Counting distance: Effects of egocentric distance on numerical perception
Reaction times in Experiment 1, as a function of response hand and numerical value, within each of the hand-position groups.In one group, the right hand was positioned on the far key and the left hand was positioned on the close key (a), while in the other group response keys were flipped (b). Standard errors are computed for the difference score (between big and small numerical values) [19], within each of the response hand conditions.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5391915&req=5

pone.0174772.g002: Reaction times in Experiment 1, as a function of response hand and numerical value, within each of the hand-position groups.In one group, the right hand was positioned on the far key and the left hand was positioned on the close key (a), while in the other group response keys were flipped (b). Standard errors are computed for the difference score (between big and small numerical values) [19], within each of the response hand conditions.
Mentions: An Anova conducted on the RT data indeed revealed a statistically significant three-way interaction, F(1,30) = 7.75, p<0.01, η2p = .21. To better understand the nature of this interaction we further conducted a two-way Anova within each of the hand-position groups. Fig 2 presents participants’ RTs as a function of hand (Right/Left) and numerical value (Big/Small), within each of the hand-position groups (N = 16). As can be clearly seen, when the right hand was positioned on the far key and the left hand was positioned on the close key (Fig 2A), a typical SNARC effect was obtained, F(1,15) = 14.47, p<0.005, η2p = 0.49, stemming from shorter RTs to big than to small numbers responded with the right hand, and to small than big numbers responded with the left hand (t(15) = 2.86, 2.5, respectively; p<0.05 using Tukey post-hoc criterion). As explained above, this Left-Right spatial-numerical mapping was confounded with a Near-Far mapping. However, when the right hand was positioned on the close key and the left hand was positioned on the far key (Fig 2B), the results pattern flipped. Rather than obtaining the typical Left-Right SNARC effect, the statistically significant interaction supported a Near-Far spatial-numerical mapping, F(1,15) = 6.56, p<0.03, η2p = 0.30. That is, responses were faster to big than to small numbers when responded with the left (far) hand, and were faster to small than to big numbers when responded with the right (close) hand (t(15) = 2.86, 2.5, respectively; p<0.05 using Tukey post-hoc criterion). Taken together, these findings strongly support a Near-Far spatial-numerical response mapping, which dominated a Left-Right mapping typically observed when participants are requested to respond to a central digit with left and right responses. It appears that when using a close-to-far response axis, rather than a left-to-right one, the latter axis becomes irrelevant to task requirements and is thus ineffective in its influence on number magnitude representation.

View Article: PubMed Central - PubMed

ABSTRACT

Numerical value is long known to be associated with a variety of magnitude representations, such as size, time and space. The present study focused on the interactive relations of numerical magnitude with a spatial factor which is dominant in everyday vision and is often overlooked, namely, egocentric distance, or depth. We hypothesized that digits denoting large magnitudes are associated with large perceived distances, and vice versa. While the relations of numerical value and size have been long documented, effects of egocentric distance on numeral perception have been scarcely investigated, presumably due to the difficulty to disentangle size and depth factors within three-dimensional visual displays. The current study aimed to assess the potential linkage between egocentric distance and number magnitude, while neutralizing any perceived and/or physical size parameters of target digits. In Experiment 1, participants conducted a numeral size-classification task (&lsquo;bigger or smaller than 5&rsquo;), to which they responded with a near-to-body or a far-from-body key. Results revealed shorter responses for small than for large numbers when responded with a key positioned close to the body, and for large than small numbers when responded with a key positioned far from the body (regardless of hand-key mapping). Experiment 2 used verbal stimuli denoting near/remote concepts as irrelevant primes to target digits, further demonstrating a priming effect of conceived distance on numerical value processing. Collectively, our results suggest that distance magnitudes are associatively linked to numerical magnitudes and may affect digit processing independently of the effects of visual size.

No MeSH data available.


Related in: MedlinePlus