Solidity principle and manual catching in 10-month-old infants.

The research evaluated 10-month-old infants' capacity-to regulate their catching behavior according to the solidity principle as defined by Spelke. Twelve infants were observed in three conditions in which babies had to reach for an object placed behind an open box. In a first condition, the. object was smaller than the box : It could be freely displaced through the box (Possible situation). In a second condition, the object was taller than the box : It could not be freely displaced through the box without violating the solidity principle (Impossible situation). In a third situation, babies had to reach for the taller object placed behind a bigger box but still allowing a free displacement of the object through it (control condition). Latency and number of manual captures were recorded for each situation during three successive trials. Results reveal that during the first trial, latency of the first capture does not vary across to the three conditions. During the two following trials, latency increases for the impossible situation whereas it decreases, conjointly for possible and control situations. Results reveal that during the first trial,, the impossible situation induces more captures than possible and control situations. During the two next trials, the number of captures decreased progressively for the impossible condition but remained constant for the-possible and control conditions. Taken together, the results provide evidence that 10-month-old infants do not use the solidity principle before initiating a reaching action.