Involuntary attention shifting is a fundamental function that allows one to orient to unexpected and potentially harmful changes in the environment. As the noted Russian physiologist Ivan Pavlov observed, without this "what-is-it reflex," many species would not be able to survive in their environments. This observation remains just as true today in our brick-and-mortar times as it did when our ancestors had to hunt for their food. Yet despite its survival value, the involuntary switching of attention to environmental stimuli needs to be controlled when concentrating on goal-directed tasks. A study in the December issue of Alcoholism: Clinical & Experimental Research explores the cerebral connection between alcoholism and distractibility.
"Psychological tests may be used to reliably assess several cognitive functions and dysfunctions," explained Kimmo Alho, professor of psychology at the University of Helsinki. "However, many attention-related processes (such as the ability to selectively attend to certain stimuli in one’s environment) or distractibility (the tendency to involuntarily switch attention to new stimuli in the environment) are quite difficult to measure objectively with such tests. One of the reasons for this is that attention is involved in several cognitive functions, such as perception and memory."
Researchers from Finland, Germany and Sweden used electroencephalogram (EEG) electrodes placed on the scalps of study participants (alcoholics and social drinkers) to record brain responses called event-related brain potentials (ERPs), which are small voltage changes measured in microvolts. Participants were asked to discriminate between two tones of different durations in a measured reaction-time task, and to ignore occasional, varied frequency changes in the same tones. ERPs, EEG changes related to the neural processing of these stimulus changes, and participant disclosure of involuntary shifts in attention were measured simultaneously.
"The behavioral results indicated that the alcoholics were more prone to distraction," said Jyrki Ahveninen, a doctoral candidate in psychology at the University of Helsinki and lead author of the study. "This was indicated by increased reaction times to ‘unexpected’ task-irrelevant stimulus changes. Such a phenomenon is basically similar to the distractibility that can be caused by an abrupt noise when, for example, someone is trying to concentrate on reading."
"The distraction was seen as prolonged reaction times," added Alho. "That is, slowed performance in the sound discrimination task after the to-be-discriminated sound’s pitch was occasionally different from the preceding sounds. Non-alcoholic subjects were distracted, but less so than the alcoholics."
One of the ERP responses that researchers were particularly interested in is called "mismatch negativity" (MMN), a negative-polarity brain wave elicited within 200 milliseconds by any change in stimulus. MMN is a pre-attentive ERP component that discloses different phases of detection and orientation to a stimulus change, such as a pitch change in a monotonously repeating sound. Researchers believe that MMN is generated by a mismatch between a deviant sound (such as a higher-pitch) and the memory trace of the preceding sound that has been stored for some seconds.
"The biological and highly significant functional role of this mismatch process," said Alho, "is probably to initiate an involuntary attention switch toward a new event in one’s environment to evaluate its potential relevance. It could, for example, be a sign of danger." Alho added that the MMN brain response to the pitch changes was larger in the alcoholics than in the non-alcoholics. "This indicates that the auditory-cortex and/or frontal-cortex mechanisms involved in the pre-attentive pitch-change discrimination that generates MMN were more reactive to pitch changes in the alcoholics, which presumably explains the enhanced distraction caused by these pitch changes in the alcoholics."
Both Ahveninen and Alho believe this research helps to clarify that, for alcoholics, the biologically based mechanisms that lead to involuntary switching of attention to changes in the acoustic environment seem to be sensitized.
"The results seem to suggest that distractibility in alcoholics," said Alho, ‘has a determinable neurophysiological basis and might be caused by enhanced involuntary attention to task-irrelevant stimuli rather than by an inability to focus attention to a current task, or by a decreased motivation to perform cognitive tasks."
In addition, Ahveninen’s study found a significant statistical association between distractibility and early onset of drinking. "Tentatively," said Ahveninen, "this suggests that patients who begin to drink heavily in their teens are particularly susceptible to developing impairments in their brain circuits that are related to attention. Earlier research has suggested that frontal brain regions, which are important to attention-related functions, are still slightly ‘immature’ during the early teen-age years. On the other hand, it is of course possible that individuals with attention deficits are more prone to an early onset of drinking. This is one of the reasons that we are going to apply the present methodology to future studies on the causes and consequences of heavy drinking by teenage subjects."
Funding for this Addiction Science Made Easy project is provided by the Addiction Technology Transfer Center National Office, under the cooperative agreement from the Center for Substance Abuse Treatment of SAMHSA.
Articles were written based on the following published research:
Ahveninen, J., Jaaskelainen, I.P., Pekkonen, E., Hallberg, A., Hietanen, M., Naatanen, R., Schroger, E., & Sillanaukee, P. (2000, December). Increased distractibility by task-irrelevant sound changes in abstinent alcoholics. Alcoholism: Clinical and Experimental Research, 24(12), 1850-1854.