Voluntary and involuntary mental time travel in dysphoria and depression - characteristics and mechanisms
Date
03/07/2017Item status
Restricted AccessAuthor
Garcez Aurélio Dos Santos, João Pedro
Metadata
Abstract
Mental time travel (MTT) refers to an individual’s ability to mentally travel
through subjective time, autonoetically re-experiencing past events under the form of
autobiographical memories (past MTT), and pre-experiencing events as future
autobiographical representations (future MTT). MTT can occur voluntarily, whereby
a past/future autobiographical event is subjectively experienced as an intended
occurrence, or involuntarily, wherein such an event is subjectively experienced as an
unintended outcome of which the individual is aware. Studies investigating MTT’s
characteristics in dysphoria and depression show that dysphoric and depressed
individuals produce more overgeneral and negative MTT events when compared to
control groups. However, existing research has been limited to past and voluntary
MTT events, with few studies investigating involuntary MTT and future MTT in
dysphoria and depression.
The overarching aim of the present research was to compare the
phenomenological characteristics of MTT in dysphoric individuals vs. normal mood
individuals (Study 1), and in clinically depressed individuals vs. never-depressed
individuals (Study 2), with the purpose of furthering existing knowledge on MTT and
its relation with dysphoria and Major Depressive Disorder. This aim was addressed by
conducting two studies, using a 2 x (2 x 2) mixed-factorial design, with temporality
(past vs. future events) and type of retrieval (voluntary vs. involuntary events) as
within-subjects independent variables, and participant group as a between-subjects
variable. In Study 1, Portuguese university students were categorised into a dysphoric
(n=17) or a normal mood group (n=39) depending on their score on the Beck
Depression Inventory (BDI-IA) – cutoff point (≥ 10). In Study 2, clinically diagnosed
depressed patients (n=32) were recruited from a Portuguese hospital and matched for
age and gender with never-depressed control participants (n=32) recruited from the
community. The dependent variables tested were: level of spatiotemporal specificity,
self-relevance, mood and physical impact, valence, and visual perspective of the MTT
events produced. A diary methodology was used in both studies, with an open-ended
time period that lasted for a minimum of two weeks, for participants to record their
MTT events and grade them on the above mentioned variables using Likert-type
ratings. Between seven and fourteen MTT events were produced for each of the four
MTT conditions (past voluntary, past involuntary, future voluntary, future
involuntary).
Results showed that when compared to their respective control groups,
depressed, but not dysphoric participants, exhibited a clear influence of mood on
several of the phenomenological characteristics of MTT. In Study 1 there were no
statistically significant differences in the specificity, negative valence, and
mood/physical impact of the MTT events produced by dysphoric and normal mood
participants. On the contrary, in Study 2, results partially supported a lower specificity
and fully supported a greater negativity and mood/physical impact of MTT events in
depressed individuals compared with never-depressed participants. Both studies
supported the greater self-relevance of voluntary MTT events and partially supported
the hypothesised effect of type of retrieval in specificity.
These were the first studies to directly compare past and future, voluntary and
involuntary MTT events in dysphoric and depressed individuals, addressing existing
gaps in the literature. The key limitation is the relatively small sample size of both
studies, however each participant was comprehensively assessed for at least two
weeks, providing a rich set of reliable data. Despite limitations, this thesis provides
novel pilot findings that help understand the similarities and differences between
involuntary and voluntary, past and future MTT, as well as providing new information
regarding the possible role of MTT in dysphoria and depression.