Plan: Dreams and philosophical realism

Dreams and cognitive capacity

Although the dominant view is that the waking and dreaming mind differ in their cognitive capacities, there is more evidence to show that the dreaming mind has a similar cognitive capacity as that of the waking mind. That is, the dreaming mind can be just as volitional and rational as it is in waking consciousness.^[57] Lucid dreaming is a clear example where such cognitive capacity, for example, through means of self-reflection, is demonstrated in the dream state; however, functions such as reflective awareness, choice, focus, etc. are also possible in non-lucid dreaming. In one study by Kahan et al., 72 dreams produced from 16 participants were examined to determine the relationship between dreaming and waking metacognition. After conducting a procedure with specialized equipment to capture the phasic REM sleep, the participants were awakened to produce the narratives of their dreams. These narratives were transcribed for further analysis, and the participants were made to fill out a continuous-scale questionnaire to rate different cognitive abilities such as 'choice', 'attention captured suddenly', 'focused-attention', 'public self-consciousness' (concern for how one appears to others), 'reflective-awareness', ability to perceive their own thoughts (labeled as 'own thoughts and feelings'), 'own behavior', and 'external events'. The participants of this study gave a higher pervasiveness rating to their wakeful capacities in 'choice' and 'reflective awareness', but rated all other features similarly.^[57]

After completing the first questionnaire, the participants were then given a second questionnaire to rate 9 cognitive activities using the Subjective Experiences Rating Scale, Analysis of Variance (ANOVA). It was found that average pervasiveness ratings were lower for: thinking, planning, imagining, and remembering in comparison to the participants’ waking experiences.^[57] Moreover, mean pervasiveness ratings of dreaming and waking experiences did not show difference for: evaluating, talking, listening, or attending (to both external and internal events). Overall, the authors suggested that dreaming and waking experiences are more likely to differ in their executive processes such as decision making, problem solving, planning and agency but are more likely to be similar in their utilization of analytical though processes like reason, logic, reflection, contemplation, ability to compare and contrast, and evaluate. This is one such study that challenges that higher order cognitive ability is absent or suspended in REM sleep.^[57]

In other animal species

Two dogs sleeping: twitching, muscular spasms and low noises are believed by psychologists to be symptomatic of them dreaming.^[58][59]

REM sleep and the ability to dream seem to be embedded in the biology of many animals in addition to humans. Scientific research suggests that all mammals experience REM.^[60] The range of REM can be seen across species: dolphins experience minimal REM, while humans are in the middle of the scale and the armadillo and the opossum (a marsupial) are among the most prolific dreamers, judging from their REM patterns.^[61]

Studies have observed signs of dreaming in all mammals studied, including monkeys, dogs, cats, rats, elephants, and shrews. There have also been signs of dreaming in birds and reptiles.^[62] Sleeping and dreaming are intertwined. Scientific research results regarding the function of dreaming in animals remain disputable; however, the function of sleeping in living organisms is increasingly clear. For example, sleep deprivation experiments conducted on rats and other animals have resulted in the deterioration of physiological functioning and actual tissue damage.^[63]

Some scientists argue that humans dream for the same reason other amniotes do. From a Darwinian perspective dreams would have to fulfill some kind of biological requirement, provide some benefit for natural selection to take place, or at least have no negative impact on fitness. In 2000 Antti Revonsuo, a professor at the University of Turku in Finland, claimed that centuries ago dreams would prepare humans for recognizing and avoiding danger by presenting a simulation of threatening events. The theory has therefore been called the threat-simulation theory.^[64] According to Tsoukalas (2012) dreaming is related to the reactive patterns elicited by encounters with predators, a fact that is still evident in the control mechanisms of REM sleep (see below).^[65][66]

Function

Many hypotheses have been proposed as to what function dreams perform, some of which have been contradicted by later empirical studies. It has also been proposed that dreams serve no particular purpose, and that they are simply a byproduct of biochemical processes that only occur in the brain during sleep.