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Age-related differences in the Von Restorff isolation effect

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When one item is made distinct from the other items in a list, memory for the distinctive item is improved, a finding known as the isolation or von Restorff effect (after von Restorff, 1933). Although demonstrated numerous times with younger adults and children, this effect has not been found with older adults (Cimbalo & Brink, 1982). In contrast to the earlier study, we obtained a significant von Restorff effect for both younger and older adults using a physical manipulation of font colour. The effect size for older adults was smaller than that obtained for younger adults, confirming a prediction of Naveh-Benjamin's (2000) associative deficit hypothesis, which attributes age-related differences in memory performance to older adults' reduced ability to form associations. The findings are consistent with related research in which older adults demonstrate similar--but smaller--benefits for distinctive information to those for younger adults.
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Short article
Age-related differences in the von Restorff
isolation effect
Tamra J. Bireta
The College of New Jersey, Ewing, NJ, USA
Aime
´
e M. Surprenant and Ian Neath
Memorial University of Newfoundland, St. John’s, Newfoundland, Canada
When one item is made distinct from the other items in a list, memory for the distinctive item is
improved, a finding known as the isolation or von Restorff effect (after von Restorff, 1933).
Although demonstrated numerous times with younger adults and children, this effect has not been
found with older adults (Cimbalo & Brink, 1982). In contrast to the earlier study, we obtained a
significant von Restorff effect for both younger and older adults using a physical manipulation of
font colour. The effect size for older adults was smaller than that obtained for younger adults, con-
firming a prediction of Naveh-Benjamin’s (2000) associative deficit hypothesis, which attributes
age-related differences in memory performance to older adults’ reduced ability to form associations.
The findings are consistent with related research in which older adults demonstrate similar—but
smaller—benefits for distinctive information to those for younger adults.
Keywords: Ageing; Distinctiveness; Free recall; Isolation effect; von Restorff.
Normal ageing is typically associated with declines
in memory performance across a wide variety of
tasks and for many different types of informat ion
(Zacks, Hasher, & Li, 2000). Explanations for
these changes in memory performance usually
cite a deficit in some process involved in memory
formation/retrieval (e.g., forming associations;
Naveh-Benjamin, 2000) or a deficit in a general
cognitive factor (e.g., processing speed; Salthouse,
1996). None of these theories, however, propos e
that memory mechanisms operate in a fundamen-
tally different manner in older adults. Consistent
with this assumption, younger and older adults
usually show similar benefits from experimental
manipulations that improve memory, including
generation (Taconnat & Isingrini, 2004), and
levels of processing (Troyer, Ha
¨
fliger, Cadieux, &
Craik, 2006). One factor that may be an exception
Correspondence should be addressed to Tamra J. Bireta, Psychology Department, Social Sciences Building, The College of New
Jersey, 2000 Pennington Rd., Ewing, NJ, 08628, USA. E-mail: tbireta@tcnj.edu
This research was supported, in part, by National Institute on Aging Grant AG021071 awarded to AMS and IN. Portions of this
paper are based on a dissertation presented by TJB to the faculty of the Graduate School of Purdue University. We thank
E. J. Capaldi, J. S. Nairne, and R. W. Proctor for comments and discussions. Part of this work was presented at the 47th Annual
Meeting of the Psychonomic Society, Houston, Texas, November 2006.
# 2007 The Experimental Psychology Society 1
http://www.psypress.com/qjep DOI:10.1080/17470210701626608
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to this rule is distinctiveness: The available data
suggest that the benefit of distinctiveness may be
reduced—or even absent—for older adults.
There are two purposes of the research reported
here: (a) to examine age-related differences in
the effects of distinctiveness and (b) to ev aluate
the hypothesis that an associative deficit in older
adults (Naveh-Benjamin, 2000) underlies age-
related deficits in memory.
When a particular item is made distinct from
other items in a list, memory for the distinctive
item is improved. This is known as the von
Restorff effect or the isolation effect (von
Restorff, 1933). Recall of the distinctive item is
typically compared to that of a control item that
is consistent with the background items .
Isolation effects can be achieved with both physical
manipulations (e.g., size, colour, or font type) and
semantic changes (e.g., meaningfulness or cat-
egory). Numerous studies have demonstrated the
robustness of this effect using various stimul i and
methodologies (for a review, see Hunt, 1995),
and the isolation effect is reliably obtained in
college-age adults as well as in chil dren (Howe,
Courage, Vernescu, & Hunt, 2000). The size of
the isolation effect depends on several fa ctors,
including the manner in which the isolate differs
from the other items in a list. Large effects are
obtained using size, colour, and spacing manipula-
tions, and isolati on effects increase in magnitude as
the difference between the isolate and the other list
items increases (Gumenik & Levitt, 1968; see also
Hunt, 1995).
Despite the la rge liter ature on isolation effects
in children and young adults, only one published
study has examined the isolation effect in older
adults. Cimbalo and Brink (1982) displayed lists
of nine consonants to younger and older adults
for immediate written serial recall, with the
isolate lists containing a consonant in a larger
font in the fifth position. Younger, but not older,
adults recalled the isolates better than the control
items. The authors argued that older adults
noticed the size difference, but suggested that
the lack of an isolation effect reflected a deficit in
using structural information to organize the list.
The isolate, then, “may have been considered as
analogous to noise, something to be ignored” by
the older adults (p. 76).
Most current theories of ageing and memory,
including theories based on inhibition, reduced
resources, and slower speed of processing, predict
that older adults will show lower overall perform-
ance than younger adults on most episodic
memory tasks (Zacks et al., 2000). They lack,
however, a specific reason why older adults
might show a reduced or nonexistent benefit for
the isolate. In contrast, the associative deficit
hypothesis (Naveh-Benjamin, 2000) offers a
specific explanation for age-related differences in
the isolation effect. Naveh-Benjamin argued that
it is important to distinguish between memory
for a single unit and memory for associations
among units. Associations between two units can
include two items, an item and its context, two
contextual features, or “the representation of two
mental codes” (p. 1170). He proposed that the
reason older adults show poorer memory in most
episodic memory tasks is that older adults have
difficulty “merging different aspects of an episode
into a cohesive unit” (p. 1185).
Naveh-Benjamin and colleagues (Naveh-
Benjamin, 2000; Naveh-Benjamin, Hussain,
Guez, & Bar-On, 2003; Naveh-Benjamin, Guez,
Kilb, & Reedy, 2004) have demonstrated that an
important predictor of when older adults will
show worse performance than younger adults is
whether the task requires memory for units
versus memory for the association between units.
For example, compared to younger adults, older
adults recognized fewer wordnonword and
wordword pairs despite similar levels of perform-
ance for recognition of the individual items
(Naveh-Benjamin, 2000). This type of associative
deficit was replicated using pictorial stimuli
(Naveh-Benjamin et al., 2003) and face/name
pairs (Naveh-Benjamin et al., 2004). This view
has also been successful in accounting for older
adults’ reduced memory for contextual details
(for a meta-analysis, see Spencer & Raz, 1995)
using the idea that older adults can remember
individual units (i.e., the items or the contextual
features), but suffer when they must also remem-
ber associations amongst them (i.e., which
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contextual feature went with which items). Naveh-
Benjamin (2000, Exp. 3) ruled out the possibility
that older adults simply lack information about
contextual details in general by presenting words
in different fonts, followed by tests for the
words, fonts, and wordsfont relations. Older
adults showed equivalent memory for the words
and for the fonts, but a large deficit in recalling
the word font relations.
According to the associative deficit hypothesis,
age-related differences in the isolation effect are
due to the difficulty that older adults have in
associating contextual features with items such as
the colour in which a word was presen ted. The
association of the contextual element (colour) to
an item is necessary for an isolation effect to
occur because it is this contextual element that
causes the isolate to have increased distinctiveness
at retrieval (due either to items being placed in
different categories, e.g., Hunt & Lamb, 2001,
or cues uniquely specifying the isolate, e.g.,
Nairne, 2006). If older adults do not associate
contextual elements to items as well as younger
adults, then a smaller or nonexistent isolation
effect should be found for older adults.
The current experiment was designed to compare
isolation effects in younger and older adults and to
test a prediction of the associative deficit hypothesis
that older adults will show reduced isolation effects.
Participants viewed lists of 12 unrelated nouns, with
the isolate lists consisting of one item in a red font
and all other items in a black font. Immediately fol-
lowing presentation, participants recalled the items
using free written recall. In addition, two different
presentation rates were used to determine whether
older adults would show greater isolation effects
when given an increased opportunity to encode
the information.
Method
The design of the current experiment differed
from the Cimbalo and Brink (1982) study in the
following ways: First, the list items were presented
one at a time rather than simultaneously to ensure
that all items were given equal opportunity to be
encoded. Second, presentation time was held
constant across lists for a given participant rather
than varied unpredictably. Third, the isolate
manipulation involved a perceptually obvious
manipulation of colour rather than a slight size
difference (1 mm) between controls and isolates.
Finally, the test was free rather than serial recall,
a task that typically yields larger isolation effects
(e.g., Kelley & Nairne, 2001).
Participants
A total of 80 younger adults (M ¼ 19.3 years,
range 1826) and 80 older community-dwelling
adults (M ¼ 70.1 years, rang e 6089) participated
in this experiment. The younger adults were
Purdue University undergraduates who partici-
pated in exchange for course credit. The older
adults were paid $10 per hour and were recruited
from the community. The education levels of
older adults ranged from high sch ool to gradu-
ate/professional degrees, with 79% of the partici-
pants completing at least some college
coursework (highest level of education was a
high-school degree for 21% of the older adults;
some college for 15%; a college degree for 21%;
some gradu ate or professional education for 3%;
and a graduate or professional degree for 40%).
All participants reported themselves to be in
good health, and none reported using any medi-
cations that migh t interfere with cognitive
functioning.
All participants were admin istered a 20-item
vocabulary test adapted from Salthouse (1993)
and a computerized memory span task based
upon the reading span test in Kane et al. (2004)
in order to obtain an estimate of each participant’s
overall level of cognitive function ing. Typical
results obtained: There was a slight difference in
favour of the younger adults for memory span
(younger M ¼ 7.6, SD ¼ 1.1; older M ¼ 6.7,
SD ¼ 1.0), t (158) ¼ 5.35, p , .01, but older
adults did significantly better on the vocabulary
test (younger M ¼ 7.9, SD ¼ 3.4; older M ¼
13.6, SD ¼ 5.2), t(158) ¼ 8.24, p , .01.
Materials
The stimuli were 241 nouns selected from Clark
and Paivio (2004). The nouns selected were of
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AGEING AND THE ISOLATION EFFECT
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medium to high imageability (M ¼ 6.03, range
4.006.90 out of 6.90), familiarity (M ¼ 5.97,
range 4.216.92 out of 7.00), and frequency
(M ¼ 1.75, range of 1.00 to 2.00 using log
ThorndikeLorge frequency; M ¼ 1.70, range of
1.00 to 2.77 using log KuceraFrancis frequency).
Design
Age (younger, older) and presentation rate (1.5 s,
3 s) were between-subjects variables, and the
isolation manipulation of list type (isolate,
control) and serial position (112) were within-
subjects variables. Participants viewed the to-be-
remembered items one at a time in the middle of
a computer screen and were asked to read each
word silently. Each list contained 12 different
items, with each item presented for either 1.5 or
3 s and no delay between items. The items on
each list were randomly selected without replace-
ment from the 241 stimuli; thus no word was
repeated within or across lists for any individual.
All of the items in the control lists were presented
in black against a white background. In the isolate
lists, the 7th item was presented in red, and the
other 11 items were black. The isolate always
appeared in the 7th serial position to maximize
the possibility of obtaining an isolation effect for
older adults. First, fewer trials are required to
obtain reliable data than if all positions are
tested, and, second, effect sizes are likely to be
larger in middle serial positions than in earlier
and later positions (because of the absence of
primacy and recency effects). There were 20
trials in total: 10 control lists and 10 isolate lists.
List type on any given trial was random.
Procedure
Participants were told that they would see 12
words one at a time followed by the cue “please
recall the words”. They were asked to recall as
many words as possible by writing the words
down on a response sheet that contained trial
numbers and 12 numbered lines per trial. They
were informed that they could recall the items in
any order and could take as much time as necess-
ary. To proceed to the next list, the participant
clicked on a button labelled “next trial”.
Participants were tested one at a time, and the
experimenter remained in the room to ensure
compliance with the instructions.
Results
As Figure 1 illustrates, older adults clearly showed
a von Restorff isolation effect regardless of the
presentation rate. When questioned after the
experiment, all of the younger adults and all but
2 of the 80 older participants reported awareness
of the isolate.
Free recall
The data were first analysed with a 2 (age: younger,
older) ! 2 (presentation rate: fast, slow) ! 2 (list
type: control, isolate) ! 12 (serial position: 112)
Figure 1. Recall of control and isolate lists as a function of group
and serial position. The top panel shows fast presentation, and
the bottom panel shows slow presentation.
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analysis of variance (ANOVA). For this and all sub-
sequent analyses, alpha was set to .05. Younger
adults recalled more list items than older adults
(5.28 out of 12 vs. 3.99), yielding a main effect of
age, F(1, 156) ¼ 60.12, MSE ¼ 26.24. More
words were recalled with the slower presentation
rate than with the faster rate (5.05 vs. 4.22), result-
ing in a main effect for presentation rate, F(1, 156)
¼ 25.13, MSE ¼ 26.24. Overall, lists containing
the isolate were not recalled differently from
control lists (4.63 vs. 4.64), F(1, 78) , 1. Typical
primacy and recency effects were obtained, resulting
in a main effect of serial position, F(11, 1716) ¼
121.96, MSE ¼ 4.45.
The difference in recall between younger and
older adults increased from earlier to later serial
positions (collapsed across presentation rates),
with a significant interaction between age and pos-
ition, F (11, 1716) ¼ 4.66, MSE ¼ 4.45. This
occurred primarily because of the increased
recency effects that younger adults displayed with
fast than with slow presentation. List type inter-
acted with position, reflecting the isolation effect
in which the item in the 7th serial position was
better recalled in the isolate lists than the control
lists (4.94 vs. 3.33), F(11, 1716) ¼ 10.35,
MSE ¼ 2.24. Slow presentation resulted in a
memory advantage over fast presentation for
earlier, but not for later, serial positions, yielding
a significant interaction between position and
presentation rate, F(11, 1716) ¼ 4.91, MSE ¼
4.45. There were no other significant interactions.
Isolation effect
To examine the effects of age on the isolation
effect, additional analyses were performed on
recall of just the items occurring in the 7th serial
position. A 2 (age: younger, older) ! 2 (presen-
tation rate: fast, slow) ! 2 (list type: control,
isolate) ANOVA yielded main effects for all vari-
ables. More items were recalled by younger than
older adults (5.18 vs. 3.09), F(1, 156) ¼ 82.76,
MSE ¼ 4.19, and with slow than fast presentation
(4.54 vs. 3.73), F(1, 156) ¼ 12.81, MSE ¼ 4.19,
and the isolates were recalled more often than
control items (4.94 vs. 3.23), F(1, 156) ¼ 78.03,
MSE ¼ 2.69. Younger adults demon strated a
larger difference between isolates and controls
(6.26 vs. 4.09) than did older adults (3.63 vs.
2.56), resulting in a significant interaction
between age and list type, F(1, 156) ¼ 9.21,
MSE ¼ 2.69. A t test confirmed an isolation
effect for older adults, with the means for isolates
(3.63) and controls (2.56) differing significantly,
t(80) ¼ 4.29. No other interactions were signifi-
cant. The lack of a significant three-way inter-
action between age, presentation rate, and list
type, F(1, 156) ¼ 0.62, MSE ¼ 2.69, suggests
that the difference in the size of the isolation
effect for younger compared to older adults does
not depend on presentation rate.
Participant variables
The sample of older adults included many who
had graduate or professional degrees. One possible
concern is that the von Restorff effect that was
observed was driven by a subgroup of highly
educated and potentially higher performing older
participants. The older participants were divided
into two groups based on level of education. The
closest we could come to a median split that
resulted in groups with equivalent ages was to
define the “high education” group as those with
at least some graduate school (N ¼ 34, M ¼
70.41, range 60 to 82) and the “low education”
group as everyone else (N ¼ 46, M ¼ 69.85,
range 60 to 89). Both groups showed a significant
von Restorff effect, t(32) ¼ 4.02 and t(44) ¼ 2.41
for the “high” and “low”, respectively, although the
high education group had a larger isolation effect
than the low education group (2.56 vs. 3.91 com-
pared to 2.56 vs. 3.41). However, the age-related
difference remains even when the high education
group was compared to the younger adults
(4.09 vs. 6.26). Thus, high levels of education in
older adults reduces, but does not eliminate, the
age-related differences seen in the magnitude of
the isolation effect.
Because our sample included a wide range of ages
forolder adults, it was possible to examine differences
in the isolation effect between the youngold (ages
6074, N ¼ 59) and the oldold (ages 7589, N
¼ 21). Each age group showed a significant isolation
effect: 3.78 isolates versus 2.69 controls for the
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youngold, t(19) ¼ 2.53, compared to 2.19 isolates
versus 3.19 controls for the oldold, t(57) ¼ 3.97.
The magnitude of the isolation effect did not
differ, t(78) ¼ 0.15. Thus, the benefit of the isolate
appears relatively stable across older age.
Output order
One possible explanation for the higher recall of
the isolate may be that it is output earlier than
the control item, which reduces output interfer-
ence. To check for this, mean output position for
recalling the item from the 7th position (when it
was recalled) in both the control and isolate lists
was calculated (see Figure 2). A 2 (age: younger,
older) ! 2 (presentation rate: fast, slow) ! 2
(item type: control, isolate) ANOVA was con-
ducted on average output position for isolates
and controls. Of most importance, isolate items
were not output at earlier positions than control
items, F(1, 56) , 1. However, older adults
output the 7th items (collapsed across control
and isolate lists) significantly earlier than did
younger adults (position 3.7 vs. 4.4), resulting in
a main effect of age, F(1, 156) ¼ 14.22, MSE ¼
2.48. This is due to the fewer total number of
items recalled by older adults than by younger
adults. The isolated items were also output
earlier with fast presentation compared to slow
presentation (3.7 vs. 4.3), F(1, 156) ¼ 12.27,
MSE ¼ 2.48. Again, this effect occurred as a
result of the fewer items recalled with fast than
with slow presentation. There were no significant
interactions. This analysis was repeated on nor-
malized data, which takes into account the
differential levels of recall; again, no evidence of
early output of the is olated item was observed.
GENERAL DISCUSSION
Younger adults demonstrated better memory for
isolated items than did controls in lists of homo-
geneous background items, replicating the well-
known isolation effect (von Restorff, 1933). In con-
trast to the results obtained by Cimbalo and Brink
(1982), the results of the current study clearly
demonstrate a significant isolation effect for older
adults. Because of the numerous methodological
differences between the Cimbalo and Brink study
and the current experiment, it is not clear why the
effect was not obtained in their study. However,
their combination of serial recall, simultaneous
presentation, and a relatively small difference
between isolate and control items may all have con-
tributed to the difference. The current study used a
more typical methodology and found that older
adults are affected by distinctiveness in a qualitat-
ively similar way to younger adults.
Although the older adults showed a signi ficant
isolation effect, it was smaller than that of the
younger adults. These results support the predic-
tions of Naveh-Benjamin’s (2000) associati ve
deficit hypothesis. According to this view, older
adults show poorer memory in most episodic
memory tasks due to difficulty “merging different
aspects of an episode into a cohesive unit” (p.
1185). In the current experiment, memory for
each list requires associations amongst the items
and/or associations between each item and the
surrounding context, both of which will be
deficient for older adult s. This v iew, therefore,
correctly predicts overall lower performance for
older adults. Further, because older adults are
not able to assoc iate contextual elements with
specific items as well as younger adults, th ey are
not able to use these contextual features as retrieval
cues as effectively. The weaker association between
the unique colour information and the item will
reduce the isolation effect because it is this contex-
tual element that causes the isolate to have
increased distinctiveness at retrieval.
Figure 2. Proportion of responses for isolates and controls (7th
position) by output position.
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The finding of a reduced isolation effect for older
adults could also be explained by accounts that pos-
tulate processing differences between younger and
older adults, as processing differences have been
shown to affect the magnitude of the isolation
effect (e.g., Fabiani, Karis, & Donchin, 1990). For
example, one view states that distinctive processing,
defined as “processing the difference in the context
of similarity”, is more difficult for older adults (see
Smith, 2006, p. 279). This difficulty arises from the
need to process information about the item as well
as information about the relationships between the
items, which draws upon cognitive resources that
are limited for older adults. According to this view,
older adults are less likely to engage in distinctive
processing when the task requires a large amount
of cognitive resources. Therefore, in a task such as
the one in the current study that requires a large
amount of cognitive resources, older adults would
be less able to engage in the distinctive processing
that results in the isolation effect.
Most current accounts of the isolation effect
attribute it to the increased distinctiveness at
retrieval for the isolate relative to the background
items (e.g., Hunt & Lamb, 2001; Kelley &
Nairne, 2001; Nairne, 2006). Research in other
areas has found that older adults do benefit from
enhanced distinctiveness at retrieval, albeit to a
lesser extent than younger adults (e.g., Ma
¨
ntyla
¨
& Ba
¨
ckman, 1992; Smith, 2006), and it would
therefore be surprising if older adults did not
show an isolation effect. Contrary to the only
other published study, the result s reported here
show that older adults do show a typical isolation
effect, and, in parallel with findings in other
areas, the effect is reduced for older adults.
Original manuscript received 4 April 2007
Accepted revision received 27 July 2007
First published online day month year
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8 THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 0000, 00 (0)
BIRETA, SURPRENANT, NEATH
... 6 Many isolation paradigms have been developed since the phenomenon was first described: the isolated item can be different from others by differing physically (a different color or font size), semantically (meaningfulness or category) or even a taboo word presented in a list of neutral words. 7 In all cases, people demonstrate superior recall of these items when isolated. 3,8,9 Therefore, the Von Restorff effect has been demonstrated numerous times in children and adults and, although it was first considered absent in elders, 10 subsequent studies showed it is also present in older ages, albeit with a smaller effect size. ...
... 3,8,9 Therefore, the Von Restorff effect has been demonstrated numerous times in children and adults and, although it was first considered absent in elders, 10 subsequent studies showed it is also present in older ages, albeit with a smaller effect size. 7,11 Other studies have also reported the effect in a healthy elderly population, but failed to observe the effect in Alzheimer's Disease (AD) patients. 13 In all these studies, the paradigm used was the free recall of word lists, a task highly susceptible to isolation effects. ...
... We hold that the isolation effect displayed by older adults can be observed across different methodologies used to investigate this phenomenon, regardless of whether the isolated word is emotionally distinct (as in this study), or differs semantically 11 or physically from the remaining items. 7,12 In addition, we also investigated the presence of the Von Restorff effect in clinical samples with memory impairment (amnestic MCI and AD patients). Only one study studied this effect in an AD population. ...
Article
Full-text available
The Von Restorff (isolation) effect refers to a stimulus that is more likely to be remembered amongst other stimuli in memory tasks. It has been demonstrated with different age ranges and methodologies. Objective: To investigate: a) the presence of the isolation effect in elders tested with the new Brazilian Portuguese version of the Rey Auditory Verbal Learning Task (RAVLT) in which a word with potential emotional weight (mother) was introduced; b) whether isolation effects persist in memory disorders of different degrees of severity (Mild Cognitive Impairment [MCI]; Alzheimer's Dementia [AD]). Methods: The RAVLT was administered to 287 consecutive volunteers. Individuals underwent medical and neuropsychological evaluation and were further sub-grouped into normal controls (n=114), MCI (n=87) and AD (n=86) patients. One-way analysis of variance (ANOVA) and Chi-squared tests were performed. Post-hoc Tukey analysis was conducted to assess significance of group differences. Results: There were significant group effects on the learning curve. A W-shape - instead of the classical U-shape - was found for the serial position curve in all groups. Conclusion: The new Brazilian version of the RAVLT exhibited the Von Restorff effect, where this phenomenon was evident not only in older adults but also patients with MCI and AD, providing further psychometric measures for inter-group analyses.
... 76). More recent studies have reported isolation effects in older adults, but the effects were smaller in magnitude than the effects found in college-age adults (Bireta, Surprenant, & Neath, 2008;Geraci, McDaniel, Manzano, & Roediger, 2009). Bireta et al. (2008) argued that older adults lack the cognitive resources needed for Bprocessing the difference in the context of similarity^(p. ...
... More recent studies have reported isolation effects in older adults, but the effects were smaller in magnitude than the effects found in college-age adults (Bireta, Surprenant, & Neath, 2008;Geraci, McDaniel, Manzano, & Roediger, 2009). Bireta et al. (2008) argued that older adults lack the cognitive resources needed for Bprocessing the difference in the context of similarity^(p. 351; see also Smith, 2011). ...
Article
An item that is conceptually or physically different from other items in a series is often remembered well. This isolation effect has been found independent of the position of the isolated item in the list, suggesting that special attention to or processing of the isolated item is not a necessary precondition of the effect. Three experiments are reported that challenge this conclusion. In Experiment 1a, we compared memory for conceptually isolated items to memory for the same items in unrelated and homogeneous lists. Under moderately distracting conditions, isolation effects were observed with midlist but not with early isolates. In fact, early isolation impaired memory for the conceptually distinct items relative to the same items in homogeneous lists. Experiment 1b replicated this memory impairment for early conceptual isolates and extended it to nondistracting conditions. In Experiment 2, we focused on early isolation, manipulating the type of isolation and whether or not participants performed judgments of learning (JOLs). An early isolation effect was observed for numbers isolated in lists of words (and vice versa), but not for conceptual isolates. Performing the JOL task reduced the size of the early isolation effect. These results suggest that number/word stimulus contrasts are coded automatically and support an isolation effect independent of list position. However, conceptual contrasts require relational processing and will only support an early isolation effect when such processing occurs. The results of Experiments 1a, 1b, and 2 suggest that attentional resources during list presentation and a favorable retrieval environment combine to support good memory for distinctive events.
... Relative distinctiveness seems to improve older adults' memory for neutral items (the von Restorff or isolation effect), but perhaps not to the same extent as in young adults (Bireta, Surprenant, & Neath, 2008). Only a handful of studies have considered relative distinctiveness in the aging memory positivity literature, and the results are unclear. ...
Thesis
Emotional experiences are more likely to be remembered than more neutral, mundane ones. In young adults, negative information may be particularly memorable. Yet, an interesting change seems to happen in aging: As adults grow older, they may start remembering positive information more often than negative information. This positive memory bias in aging is commonly reported and is often explained in terms of changing time perspectives and motivation across the lifespan (i.e., Socioemotional Selectivity Theory). However, few studies have considered the basic interactions between memory and emotion that could influence this positivity bias. In this thesis, I examine whether certain factors partially independent of aging (i.e., semantic relatedness and distinctiveness, Study 1; mood, Studies 2-4), might influence the presence and magnitude of the positivity bias in memory. In Study 1, I explore the cognitive mechanisms required to produce the positivity bias and apply what is learned in this paper to investigate, in Studies 2-4, whether differences in mood could explain why the positivity bias occurs. In all studies, memory is measured using immediate free recall of positive, negative, and neutral pictures. In Study 1, I manipulate item interrelatedness (i.e., the extent of relatedness among pictures of a same category) and relative distinctiveness (i.e., the processing of a picture category at the same time as or in isolation from the others) to show that older adults’ emotional memory can be entirely explained by these two factors. The distinctive processing of positive pictures relative to other pictures is necessary for producing a positivity bias in older adults, which completely disappears when the distinctive processing of positive pictures is removed. Therefore, in subsequent studies I encourage the distinctive processing of items to increase the likelihood of observing a positivity bias and its possible interaction with mood. In Study 2, I test whether differences in mood predict differences in emotional memory bias in young and older adults using a video mood induction technique validated in a separate pilot study. In Studies 3 and 4, I further test the effect of mood on the positivity bias beyond any age-specific factors, by examining young adults only. This serves to reduce the likelihood of confounds that might exist between age groups (i.e., related to neurocognitive changes or decline), in order to study the true effects of mood on the positivity bias. In Study 3, I use a written priming task to experimentally manipulate mood and time perspective in young adults. In Study 4, I compare differences in naturally occurring moods and emotional memory in two separate young adult samples: university students and non-students. The experimental mood manipulations have minimal influence on the presence of a negativity bias in young adults (Studies 2 and 3), and influence to a small extent the memory advantage of positive over neutral material in older adults (Study 2). Non-student young adults show a similar preferential memory for positive material that is different from what is observed in university students, but this is not easily attributed to differences in mood (Study 4). In light of these results, I argue that the positivity effect in aging memory reflects a temporary contextual advantage for positive information that is not permanent or irreversible. Rather, it seems to depend in varying degrees on the context of study (i.e., relatedness and distinctiveness), mood, and the young-adult reference group. This has implications for how future research defines and studies the positivity effect in aging.
... Ironically, von Restorff's (1933) original experiment argues against the necessity of salience in explaining the isolation effect. As noted by Hunt (1995), most isolation paradigms have placed the isolate late in the list (e.g., Bireta, Surprenant, & Neath, 2008). However, von Restorff (1933) herself placed the isolate early in the list (i.e., serial positions 2 or 3), and subsequent research found the effect even when the isolate appeared as the first item in the list (e.g., Kelley & Nairne, 2001). ...
Article
This study contrasted two explanations of the von Restorff effect – distinctive processing and retrieval cue efficacy, which differ in their assumptions about encoding processes. A homonym, kiwi, was used as the critical word and manipulated to either be synonymous with background items, or made an isolate by orienting participants towards its alternate meaning. The orientation was done at either the encoding or retrieval stages. Experiments 1a and 1b showed that even without distinctive processing at encoding, the von Restorff effect could still occur at retrieval in the presence of an effective retrieval cue. Experiments 2 and 3 eliminated the von Restorff effect through equating cue overload between the control and isolation lists. The results support the retrieval cue efficacy account and suggest that it is not necessary to have distinctive processing to obtain the isolation effect.
... In particular, there are two common strategies used to induce primary distinctiveness: perceptual isolation and conceptual (i.e., categorical) isolation. Perceptual isolation occurs when a stimulus varies from surrounding stimuli on some physical dimension-for instance, a red-font word embedded in a sequence of black-font words (e.g., Bireta, Surprenant, & Neath, 2008), or a word with a large font size placed in a list of words with smaller font size (e.g., Kelley & Nairne, 2001). In contrast, conceptual isolation occurs when an isolate differs from other items due to its category membership, such as embedding the name of a piece of furniture (say, table) in a list otherwise composed of types of fish (e.g., trout, herring, salmon, etc.; Geraci & Rajaram, 2004). ...
Article
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The typical pattern of results in divided attention experiments is that subjects in a full attention (FA) condition perform markedly better on tests of memory than subjects in a divided attention (DA) condition which forces subjects to split their attention between studying to-be-remembered stimuli and completing some peripheral task. Nevertheless, recent research has revealed an exception wherein stimuli presented concurrently with targets in a detection task are better remembered than stimuli which co-occur with distractors. Research on this phenomenon—the Attentional Boost Effect (ABE)—has demonstrated that the ABE is reduced or eliminated for words made distinct by their word frequency or orthographic properties—forms of secondary distinctiveness. However, it is unclear how primary distinctiveness effects may interact with the ABE. The current study observed how perceptual and semantic manipulations of primary distinctiveness via the isolation paradigm interact with the ABE, and revealed these interactions to be fundamentally different than those of secondary distinctiveness. Specifically, whereas the effects of secondary distinctiveness in earlier studies were found to be redundant with the ABE, the current study demonstrated that items characterized by primary distinctiveness enhanced memory performance independently of the ABE.
Article
Résumé Une expérience a examiné les différences mnésiques liées à l’âge pour de l’information distinctive. Si un effet facilitateur d’orthographie a été obtenu quel que soit l’âge des sujets (jeunes adultes vs. personnes âgées), l’effet de bizarrerie n’a été observé en rappel libre que pour les jeunes adultes et non pour le groupe de sujets âgés (au-delà de 70 ans). Les résultats sont discutés en lien avec la théorie de la distinctivité de Hunt (2006) qui prédit que les fluctuations dans les traitements relationnels et spécifiques à l’item influenceront les effets sur la mémoire.
Article
The bizarreness effect on object recognition is a strong phenomenon, but its influence has been inconsistent for bizarre object color. In this study, we manipulated three factors in separate experiments to determine whether a color bizarreness effect on object recognition memory would occur and, if not, why. Participants first saw (i.e., learned) object pictures that were either bizarrely or typically colored; they then completed a recognition memory test. In three experiments, we then manipulated (a) degree of color bizarreness (Experiment 1), (b) the orientation task (Experiment 2), and (c) additional demands for object identification (Experiment 3). In Experiment 1, we provided 49 undergraduate participants with object pictures whose colors were typical, moderately atypical, or bizarre and found no color bizarreness effect on recognition memory even for extremely bizarre colors. In Experiment 2, we manipulated the orientation task in that 28 young adult participants expressed their preferences for the pictures on a three-point scale while another 28 participants judged how natural the pictures were. Each orientation task group better recognized typically-colored rather than bizarrely-colored objects (typicality effect). In Experiment 3, we asked 27 young adults to identify the objects during the learning phase to ensure that they paid attention to the objects’ bizarre colors; recognition memory was then unaffected by either color bizarreness or typicality. Thus, despite a general bizarreness effect in recognition memory, bizarre colors are less likely to influence object recognition memory.
Article
The present study investigated a recently introduced left-lateralized component in the event-related potential (ERP), the posterior semantic asymmetry (PSA), in the context of an isolation paradigm. The PSA is a relative negativity that is most pronounced at temporoparietal electrodes, peaks around 300 ms, and is assumed to reflect early semantic processing of visual words. A free-recall, word-list-learning paradigm was conducted. The learning list comprised two stimuli which were physically isolated from the other stimuli (by different font size or different typeface). The typical behavioral isolation effect with higher recall for isolated stimuli was observed. Furthermore, ERP effects of stimulus type and subsequent memory were analyzed. A left-lateralized negativity that matched the topography of the PSA but occurred somewhat later showed an effect of stimulus distinctiveness, with increased amplitudes for isolates, thus suggesting their deeper semantic processing. However, PSA amplitude did not predict subsequent recall. Unlateralized ERPs replicated previous findings of a greater late frontal positivity during elaborated encoding of both isolated stimuli and subsequently recalled stimuli. This recall effect was greater for isolated than standard stimuli. We argue that physical distinctiveness during encoding facilitates recall to the extent that it promotes the frontally-mediated processes that predict better recall in general.
Article
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Any mature field of research in psychology-such as short-term/working memory-is characterized by a wealth of empirical findings. It is currently unrealistic to expect a theory to explain them all; theorists must satisfice with explaining a subset of findings. The aim of the present article is to make the choice of that subset less arbitrary and idiosyncratic than is current practice. We propose criteria for identifying benchmark findings that every theory in a field should be able to explain: Benchmarks should be reproducible, generalize across materials and methodological variations, and be theoretically informative. We propose a set of benchmarks for theories and computational models of short-term and working memory. The benchmarks are described in as theory-neutral a way as possible, so that they can serve as empirical common ground for competing theoretical approaches. Benchmarks are rated on three levels according to their priority for explanation. Selection and ratings of the benchmarks is based on consensus among the authors, who jointly represent a broad range of theoretical perspectives on working memory, and they are supported by a survey among other experts on working memory. The article is accompanied by a web page providing an open forum for discussion and for submitting proposals for new benchmarks; and a repository for reference data sets for each benchmark. (PsycINFO Database Record
Thesis
Le travail de recherche présenté dans cette thèse considère la mémoire humaine comme un système unique et non abstractif qui reflète l’ensemble de nos expériences sous forme de traces épisodiques multimodales. Les objectifs de cette thèse sont multiples, mais le principal est de montrer qu’un effet robuste de la mémoire, l’effet de distinctivité, peut émerger aussi bien dans les tâches implicites que dans les tâches explicites et que cet effet s’expliquerait en termes de mécanismes spécifiques (activation et intégration multimodales) et non pas en termes de systèmes mnésiques sous-jacents.Trois séries d’expériences ont été élaborées. Dans une première série, nous avons manipulé l’information contextuelle extrinsèque associée à ces concepts. Une tâche de catégorisation nous a permis de démontrer que l’effet de distinctivité pouvait se manifester avec une tâche implicite de mémoire.Dans une deuxième série d’expériences, nous avons manipulé la distance entre des images à catégoriser dans une phase d’encodage. Ainsi, les images apparaissaient soit plus éloignées les unes des autres, soit plus proches. Suite à une récupération implicite, nous avons mis en évidence que notre hypothèse de distinctivité spatiale était validée, c’est-à-dire que les items spatialement plus distinct lors de l’encodage sont associés à des performances supérieures en phase test.Dans la troisième série d’expériences, nous avons mis en évidence que lesperformances liées à l’effet de distinctivité dans les tâches implicites et explicites de mémoire variaient selon différents niveaux d’intégration des dimensions sensorielles. Cette idée a été testée en rappel libre, en décision lexicale et en reconnaissance.Au final, nos résultats expérimentaux suggèrent que les performances issuesdes tâches implicites et explicites peuvent être expliquées au sein du même système mnésique unique. Ainsi, les processus d’intégration seraient à l’origine de ce phénomène.
Article
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A theory is proposed to account for some of the age-related differences reported in measures of Type A or fluid cognition. The central hypothesis in the theory is that increased age in adulthood is associated with a decrease in the speed with which many processing operations can be executed and that this reduction in speed leads to impairments in cognitive functioning because of what are termed the limited time mechanism and the simultaneity mechanism. That is, cognitive performance is degraded when processing is slow because relevant operations cannot be successfully executed (limited time) and because the products of early processing may no longer be available when later processing is complete (simultaneity). Several types of evidence, such as the discovery of considerable shared age-related variance across various measures of speed and large attenuation of the age-related influences on cognitive measures after statistical control of measures of speed, are consistent with this theory.
Article
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The effects of isolation and generation on memory for order were investigated in 4 experiments. Experiments 1 and 2 examined the effect of isolation on order retention. Previous investigations in this area have yielded equivocal results. Experiments 1 and 2 revealed that isolation enhances memory for order: Isolated items were repositioned more accurately than comparable items in control lists. Experiments 3 and 4 investigated the effect of generation on order retention. These experiments revealed that generation can enhance, disrupt, or have no effect on memory for order, depending on the relative number of generated items appearing within a list Implications of these results for general theoretical accounts of isolation effects in memory are discussed. A simplified version of the feature model (J. S. Nairne, 1990) is shown to provide a general account of isolation effects.
Article
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The isolation effect is a well-known memory phenomenon whose discovery is frequently attributed to von Restorff (1933). If all but one item of a list are similar on some dimension, memory for the different item will be enhanced. Modern theory of the isolation effect emphasizes perceptual salience and accompanying differential attention to the isolated item as necessary for enhanced memory. In fact, von Restorff, whose paper is not available in English, presented evidence that perceptual salience is not necessary for the isolation effect. She further argued that the difference between the isolated and surrounding items is not sufficient to produce isolation effects but must be considered in the context of similarity. Von Restorff's reasoning and data have implications for the use of distinctiveness in contemporary memory research, where distinctiveness is sometimes defined as perceptual salience and sometimes as a theoretical process of discrimination. As a theoretical construct, distinctiveness is a useful description of the effects of differences even in the absence of perceptual salience, but distinctiveness must be used in conjunction with constructs referring to similarity to provide an adequate account of the isolation effect and probably any other memory phenomena.
Article
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Adult age differences in the consistency effect were examined in 3 experiments. The consistency effect refers to items inconsistent with expectations being better remembered than items consistent with expectations. Younger and older adults walked into an office room and viewed objects that varied in their consistency with expectation. Immediate and delayed recognition tests on item information (i.e., distractors were defined by their semantic identity) revealed that both age groups recognized unexpected items better than expected items. However, when recognition of token information was requested (i.e., distractors were defined by their physical appearance), younger adults, in contrast to older adults, exhibited consistency effects. Also, under divided attention, young adults revealed the same pattern of data as did elderly adults under full attention. The results are discussed in terms of capacity-related differences in distinctive encoding.
Chapter
Younger adults often perform better than older adults do on memory tests. Researchers interested in these age-associated performance differences have at times drawn concepts from the "mainstream" research (that is, research that focuses on younger adults) and applied these concepts to explain why older adults frequently do not remember as well as younger adults. This chapter looks at attempts to explain age differences in episodic memory as a function of relational and item-specific processing, and in some cases both kinds of processing. The focus is on studies comparing intentional retrospective memory in healthy younger (generally less than 30 years of age) and older adults (generally 60 years of age and older). The chapter primarily addresses three questions. First, are there age-related differences in item-specific processing? Second, are there age-related differences in relational processing? And finally, are there agerelated differences in distinctive processing? The chapter concludes by relating three of the four points concerning distinctiveness raised by R. Reed Hunt to the literature on memory and aging.
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An associative hypothesis to explain and predict older adults' deficient explicit episodic memory performance was outlined and tested. The hypothesis attributes a substantial part of older adults' deficient memory performance to their difficulty in merging unrelated attributes-units of an episode into a cohesive unit Although each of the components can be memorized to a reasonable degree, the associations that tie the attributes-units to each other grow weaker in old age. Four experiments are reported that provide (a) a converging validity to the hypothesis by demonstrating this associative deficit for both interitem relationships and intraitem relationships and (b) a discriminant validity to the hypothesis by contrasting and testing competing predictions made by the associative hypothesis and by alternative hypotheses. The implications of these results to older adults' episodic memory performance arc discussed.
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Article
Subjects were instructed to use either rote or eleborative strategies to memorize words in a Von Restorff paradigm. When instructed to use rote strategies, subjects displayed a higher Von Restorff effect and a lower recall performance than when instructed to use elaborative strategies. Furthermore the amplitude of the P300 component of the event-related brain potential predicted subsequent recall only when subjects used rote strategies. When subjects used elaborative strategies, the relationship between P300 amplitude and subsequent recall was not observed. These results confirm and expand, in a within-subjects design, the results reported by Karis, Fabiani and Donchin (1984) who capitalized on different strategies used by different subjects. These results also lend support to a 3-phase model of the Von Restorff effect.
Article
College students (n = 36) and elderly persons (n = 28 females, eight males; 60–83 years old) were compared on an immediate-memory task involving an outstanding item in the center of the array. The college students remembered the outstanding item well, the elderly did not. Both groups displayed better overall performance for the list containing the outstanding item. The results are discussed in terms of differences in processing strategies.