I know that to be true. I once "memorized" (yeah right) the general ranger station map after a friend turned back with the copy. Later, I encountered a deliberately twisted trail sign. A five mile hike then turned into a nine mile hike during August heat in Texas.
After that sweaty and thirsty lesson, I order and use the USGS topographic map for any area that I am hiking- and also take two copies of the ranger station map.
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There might not of been a drug or poison. Rather, there could have been collective panic, stress and tunnel vision compounding each other and snowballing.
In hiking groups, this can lead to the abandonment of needed gear, the rejection of clearly viable courses of action, energy wasted trying to do everything at once- but actually doing nothing, obessive tunnel vision on a risky or contradictory solution as being the "only solution", obsessively retaining un needed gear etc.
My guess is that one of the adults started to falter. This produced stress. But.... the presence of and danger to the baby snowballed the stress into stress approximating close combat. The adults had probably never experienced anywhere near this level of stress in the past.
Sadly, on this occasion, panic might have set in resulting in tunnel vision, contradictory efforts, energy wasted on doing everything, but accomplishing nothing. Then factor in the heat. Heat can be stullifying- like thinking in slow motion. The second adult then started to falter and things got worse.
I experienced some of the above on a hike. Many points of logic said to ignore the sign (twisted) and take the trail off the mesa. A brief backtrack confirmed the logic. My mind just kept going into "re-set mode.
