The present study was aimed at complementing the previous studies by examining the impact of hypoxia on information integration capacities in daily life settings. The chosen judgment situation was borrowed from elementary physics and concerned the relationships between mass, volume and density. It was chosen because these three concepts are some of the most commonly used ones in everyday life. Although they are taught in school in a systematic way, people, as a general rule, construct a representation of these notions much before the classroom exposure to them, and develop these notions during their whole lifetimes. Intuitive notions of mass or density are crucial to everyday actions such as taking, lifting, moving, and carrying. Over the course of development, children, adolescents, and adults, necessarily perform these types of actions countless numbers of times. This enables them to build up a representation of the functional relationships between mass and volume and/or mass and substance (density) and/or volume and substance. Another reason why this situation was selected is that the many findings as regards the perceived relationships between these concepts, obtained in previous studies among children, adolescents, and young and older adults (Chartier, Mullet, & Grandjean, 1991; Léoni & Mullet, 1993; Léoni, Mullet, & Chasseigne, 2002; Mullet & Gervais, 1990) offered a background for the present study.

In physics, the relationship between mass, volume and density can be expressed by the following equation: Mass = Volume x Density. The right hand panel in Figure 1 graphically expresses the multiplicative character of the relationship expressed in this equation. On the horizontal axis are three density levels. On the vertical axis are theoretical mass values. The three curves correspond to three possible volumes. All three curves are ascending: The higher the density of an object, the higher the mass. Curves are clearly separated: The larger the volume, the higher the mass. In addition, the three curves form a linear fan open to the right with the large volume curve on the top and the small volume curve on the bottom. Previous studies (e.g., Léoni et al., 2002) have shown that a majority of young adults are able to integrate volume and density information in a correct, multiplicative way.

The Volume = Mass / Density equation is obtained by simple derivation from the preceding equation. For a physicist, these two equations are equivalent. Switching from one to the other is simply a matter of fairly trivial rewriting. From an information integration perspective, however, these two equations are far from being equivalent. Intuitive mastery of the Volume equation presupposes: a) as for the Mass equation, recognition of the direct relationship between mass and volume, and b) recognition of an inverse relationship between density and volume (the greater the density, the lower the volume, at constant mass). The center panel in Figure 1 graphically expresses the divisive character of the relationship expressed in the Volume equation. All three curves were descending: The higher the density of an object, the lower the volume. Curves were clearly separated: The higher the mass, the larger the volume. In addition, the three curves formed a linear fan open to the left with the high mass curve on the top and the small mass curve on the bottom. Previous studies (e.g., Léoni et al., 2002) have shown that only a minority (20%) of young adults are able to integrate mass and density information in a correct, divisive way. A majority of them integrate both pieces of information in a subtractive way (mass minus density). In other words, the volume condition represents, from a judgmental viewpoint, a much more difficult situation than the mass condition.

Figure 1 Figure 1 Theoretical patterns illustrating the physically correct relationship between mass, volume and density

The Density = Mass / Volume equation can in the same way be obtained by derivation from the Mass equation. The same comments made for the Volume equation apply to the Density equation. The right hand panel in Figure 1 graphically expresses the divisive character of the relationship expressed in this equation. Previous studies (e.g., Léoni et al., 2002) have shown that only a minority (21%) of young adults are able to integrate mass and volume information in a correct, divisive way. As in the preceding case, a majority of them integrate both pieces of information in a subtractive way (mass minus volume).

The patterns of estimations observed in the Mass condition and for each altitude level are shown in the top raw of Figure 2. In each of the three panels, the pattern was reminiscent of the theoretical one shown in Figure 1. An ANOVA with an Altitude x Volume x Density, 3 x 3 x 3 design was conducted on the raw data. As shown in Table 2, the Volume x Density interaction was significant and concentrated in its bilinear component but no interaction involving the altitude factor was significant. Each individual data pattern was subsequently analyzed. Out of the 42 patterns (14 x 3), 34 (81%) were clearly diverging on the right: 10 in the baseline situation, 13 in the 2400 m situation, and 11 in the 4400 m situation.

The patterns of estimations observed in the Volume condition are shown in the second raw of Figure 2. In each of the three panels, the pattern was different from the theoretical one shown in Figure 1. It was a pattern of parallelism. The Mass x Density interaction was not significant. The Altitude x Mass interaction was significant, and concentrated in its bilinear component. In the baseline situation, the effect of mass was stronger than in the 4400 m situation. In the baseline situation, the difference between mean judgments when the mass was high and mean judgments when it was low was 15.07 – 3.67 = 12.6. In the 4400 m situation, it was 14.4 – 3.93 = 10.47. No other interaction involving the altitude factor was significant. Visual inspection of individual patterns showed that only 16 (38%) were, as in Figure 1, clearly diverging on the left: five in the baseline situation, six in the 2400 m situation, and five in the 4400 m situation.

The patterns of estimations observed in the Density condition are shown in the bottom raw of Figure 2. As in the volume condition, the pattern was a pattern of parallelism. The Mass x Volume interaction was significant but its bilinear component was not. No other interaction involving the altitude factor was significant. Inspection of individual patterns showed that only three (7%) were, as in Figure 1, clearly diverging on the left: one in each situation.

This study was the first one to examine the effect of hypoxia on information integration capacities. Contrary to our expectations, no difference in performance was found between the three experimental sessions. In the Mass condition, the mean pattern of judgments was similar to the one reported in Léoni et al. (2002), and the percentage of participants who integrated the volume and density information in a correct, multiplicative way was higher (81%) than the one found among 20-35-year-old participants (61%) in this study, which can be attributed to the fact that all participants were university students. In the Volume condition, the percentage of participants who integrated the mass and density information in a correct, divisive way was also higher (38%) than the one (20%) found in Léoni et al. (2002)’s study. Finally, in the density condition, the percentage of participants who integrated the mass and volume information in a correct way was somewhat lower (7%) than the one (21%) found in Léoni et al. (2002)’s study.

Figure 2 Figure 2 Patterns of results showing the perceived relationship between mass, volume and density in the three conditions and the three levels of altitude

The lack of any clear effect of hypoxia on information integration capacities cannot be attributed to the level of difficulty of the tasks. Inferring the mass of an object from volume and density information is, as already stated above, a judgment task that is quite easy: Ninth-grade students have been shown to be able to perform it in a correct way (Léoni & Mullet, 1993). However, inferring the volume of an object from mass and density information or inferring the density of an object from mass and volume information are judgment task that are much more difficult. Both judgments tasks were demanding, and previous studies have shown that a variable that is classically associated with information processing capacities such as age directly impacts on performance. An effect of hypoxia on information integration, if such an effect existed, should have manifested itself through the emergence of non-integration patterns as was found in Léoni et al.’s (2002) older participants.

As already stated, the difference of findings in literature on the effect of hypoxia on high cognitive process has been mainly explained by divergences in the methods used (Davranche et al., 2016). In many situations, however, no significant effects on cognitive performance have, as in the present study, been detected (Hewett, Curry, Rath, & Collins, 2009; Komiyama et al., 2015; Latshang et al., 2013; Legg et al., 2014; Pavlicek et al., 2005; Tripathi, Apte, & Mukundan, 2005). It can, therefore, be safely concluded that people’s information integration capacities are not affected by hypoxia, even if acclimatization to it has not taken place, and as far as it is not too severe; that is, corresponding to an altitude that is lower than 4500 m.