Variables That Influence the Generation of Random Sequences: An Update

Abstract

This article updates Tune's 1964 review of variables influencing human subjects' attempts at generating random sequences of alternatives. It also covers aspects not included in the original review such as randomization behavior by patients with neurological and psychiatric disorders. Relevant work from animal research (spontaneous alternation paradigm) is considered as well. It is conjectured that Tune's explanation of sequential nonrandomness in terms of a limited capacity of short-term memory can no longer be maintained. Rather, interdependence among consecutive choices is considered a consequence of an organism's natural susceptibility to interference. Random generation is thus a complex action which demands complete suppression of any rule-governed behavior. It possibly relies on functions of the frontal lobes but cannot otherwise be "localized" to restricted regions of the brain. Possible developments in the field are briefly discussed, both with respect to basic experiments regarding the nature of behavioral nonrandomness and to potential applications of random-generation tasks.

Random number generation deficits in patients with multiple sclerosis: Characteristics and neural correlates

“…On a behavioral level, it can be concluded that even when compensating for difficulties by slowing the rate at which they produced numbers, MS patients commit rule breaks and cannot sufficiently suppress a counting algorithm. RNG may be a useful tool in the clinical monitoring of MS. As the task is highly resistant to practice effects (Brugger, 1997;Jahanshahi, Saleem, Ho, Dirnberger, & Fuller, 2006), it may prove particularly suitable for monitoring cognitive capacity over time.…”

“…Instructions of a random number generation (RNG) task require subjects to arrange numbers in a sequence "as random as possible", implicitly asking to avoid any algorithm and to disobey any rule. Under a huge range of conditions (Brugger, 1997) healthy volunteers were found unable to follow these instructions, and so were patients with various neuropsychiatric diseases (Brown, Soliveri, & Jahanshahi, 1998;Brugger, Monsch, Salmon, & Butters, 1996;Ho, Sahakian, Robbins, & Barker, 2004;Salamé & Danion, 2007;Spatt & Goldenberg, 1993). A limited capacity of working memory and executive functions have been implied in the failure to produce unpredictable, or random sequences of response alternatives (Baddeley, 1966(Baddeley, , 1998Joppich et al, 2004;Maes, Eling, Reelick, & Kessels, 2011;Miyake et al, 2000).…”

Nonstereotyped Responding in Positive Schizotypy after a Single Dose of Levodopa

“…During the generation of random sequences, patients with schizophrenia (Salamé et al, 1998;Brugger, 1997 for overview), healthy participants after amphetamine administration (Ridley et al, 1988), and healthy participants with elevated schizotypal features (Brugger et al, 1990;Avons et al, 2003) showed more pronounced response biases compared to their respective controls.…”

Reinforced Variability in Animals and People: Implications for Adaptive Action.

“…In many studies over the past 60 years, human participants have been asked to respond randomly (e.g., randomly call out "heads" and "tails," or the digits zero through nine, or randomly press eight buttons), the results being that, in almost every case, response distributions were easily distinguished from random (Brugger, 1997;Nickerson, 2002). With only one exception, participants in these studies received neither feedback nor reinforcement for approximating a random distribution-they were simply instructed to respond randomly.…”