Edited by: Gemma Casadesus, Case Western Reserve University, USA
Reviewed by: Marcia Chaves, Federal University of Rio Grande do Sul, Brazil; Ana M. Coto-Montes, University of Oviedo, Spain; Ekrem Dere, University Pierre and Marie Curie Paris 6, France
*Correspondence: Yoko Ishigami, Department of Psychology, Life Science Centre, Dalhousie University, 1355 Oxford Street, Halifax, NS, Canada B3H 4R2. e-mail:
This is an open-access article subject to a non-exclusive license between the authors and Frontiers Media SA, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and other Frontiers conditions are complied with.
Ishigami and Klein (
Posner and Petersen (
Attention has been of interest in the literature on aging because aging in humans includes a multidimensional process of attentional changes. However, the precise empirical relationship between aging and attention remains somewhat inconclusive (for reviews, see Kok,
Alertness can be subdivided into phasic and tonic alertness. Tonic alertness or sustained attention is a state of general wakefulness or vigilance and refers to one’s ability to sustain attention over a period of time. Phasic alertness involves a rapid change in mental state and physiological state following a presentation of a warning signal, and prepares the individual for fast reactions (Posner,
Orienting, which can be controlled by primarily exogenous or endogenous means, involves selective allocation of attention to a source of signals in space (Posner,
Executive attention involves conflict resolution and control over decision-making, error detection, and habitual response inhibition (Norman and Shallice,
Typically, the different components of attention have been examined using different paradigms. Thus, three different experiments may be conducted to examine these attention components within the same individuals. In that case, it is not possible to examine how these components interact. The ANT, however, enables us to examine these attention components all at once and to examine how they interact. The original ANT was developed by Fan et al. (
Essentially, the ANT (and the ANT-I) is a combination of the Posner spatial cueing task (Posner,
ANT | ANT-I | |
---|---|---|
Auditory signal | NA | Tone |
No tone | ||
Cue condition (ANT) | No cue | No cue |
Center cue | ||
Visual cue (ANT-I) | Double cue | Valid |
Spatial cue | Invalid | |
Target congruency | Neutral | Congruent |
Congruent | Incongruent | |
Incongruent | ||
Alerting | No cue – double cue | No tone – tone |
Orienting | Center cue – spatial cue | Invalid – valid |
Executive | Incongruent – congruent | Incongruent – congruent |
Studies of aging using the ANTs are limited. Jennings et al. (
Fernandez-Duque and Black (
These studies using the ANT do not support observations in literature that aging has relatively little effect on phasic alertness (e.g., Rabbitt,
These studies show an importance and usefulness of the ANT for studying and comparing the attention networks with wide range of populations. One class of situation for which the ANT might be useful is when repeated testing is required. Researchers, for example, may be interested in developing training programs to overcome age-related impairments in attention. To assess the efficiency of such a program, repeated testing would be required. Researchers have also been interested in evaluating the effects of attention training or rehabilitation on the specific components of attention in clinical populations (e.g., Robertson et al.,
Despite the use of the ANT in pre-/post-testing (Jha et al.,
Replicating the method used by Ishigami and Klein (
Ten participants (four females and six males) took part in the current experiment. They were recruited from the local community paid for their participation ($10.00/session). The participants ranged in age from 65 to 76 (mean = 69.1 and SD = 3.6). All participants self-reported to be physically and mentally healthy (i.e., not having received a diagnosis of any mental disorders by a health practitioner) and to have normal or corrected-to-normal vision. All participants completed an informed consent form and the study was approved by the Dalhousie Sciences and Humanities Human Research Ethics Board.
We used the program written in Python programming language by Michael A Lawrence. A 17″ MacBook Pro controlled stimulus presentation and response collection. The ANT is based on a program developed by researchers at the Sackler Institute for Developmental Psychology. The ANT-I is based on a program developed by Callejas et al. (
The sequence of events for both tests can be seen in Figures
The instructions (both oral and written) emphasized the importance of quick and accurate responding. The participants were told to maintain fixation at the fixation cross all the time. They were encouraged to attend when and where indicated by the cues in the ANT. The experimenter was present only at the beginning of each session in the testing room to start the experiment and to answer participants’ questions regarding the instructions. In both the ANT and the ANT-I, feedback following errors was given visually only in the practice blocks. Participants performed both versions of the ANT in each session, which lasted about an hour and this was repeated 10 times (i.e., 10 days). The ANT and the ANT-I were administered in an alternating order across sessions. In addition, the order of the ANTs was counterbalanced across the participants. Intervals between consecutive sessions were not fixed and the mean interval was 6.7 days (SD = 5.1).
For each participant, trials with improper responses (e.g., responses made before the target was presented) or trials with no responses were excluded (2.0%). Then, mean correct RT after eliminating extreme values (less than 200 ms) and more than 1700 ms: less than 0.1% of the total analyzable data) and mean error rate were computed and subjected to analyses. Table
No cue | Center | Double | Spatial | |
---|---|---|---|---|
Congruent | 726 (0.002) | 699 (0.002) | 668 (0.004) | 626 (0.005) |
Incongruent | 808 (0.011) | 793 (0.010) | 774 (0.013) | 719 (0.018) |
Neutral | 682 0.007) | 637 (0.005) | 610 (0.008) | 569 (0.007) |
To permit comparison with the literature (which typically only has one session) analyses were done separately for Session 1 and Sessions 1–10. ANOVAs were used to examine stability (Do effects change over the 10 sessions?) and isolability (Do conditions interact?), and isolability was also analyzed using correlation.
The mean correct RT and the mean error rate were submitted to ANOVAs with cue condition (central, spatial, double, and no cues), and target congruency (neutral, congruent, and incongruent) as repeated-measures factors; Session (1–10) was also a factor for the Sessions 1–10 analyses.
RT | Alerting | Orienting | Error rate | Alerting | Orienting |
---|---|---|---|---|---|
Orienting | −0.02 | Orienting | 0.60 | ||
Executive | −0.03 | −0.13 | Executive | 0.35 | 0.07 |
Orienting | 0.46 | Orienting | 0.77 |
||
Executive | −0.03 | −0.12 | Executive | −0.16 | −0.65 |
Orienting | 0.10 | Orienting | −0.10 | ||
Executive | 0.14 | −0.11 | Executive | 0.45 | −0.38 |
Orienting | −0.26 | Orienting | −0.28 | ||
Executive | −0.27 | 0.07 | Executive | −0.24 | −0.24 |
Figure
First, reliability was examined by correlating the first two sessions to allow comparison with the original ANT study’s correlation analysis between Sessions 1 and 2 (Fan et al.,
With RT, the correlation between Sessions 1 and 2 was significant for the alerting and the orienting networks (Table
Network | S 1–2 |
S 1–2 |
S 1–2 |
S 1–10 |
S 1–10 |
||
---|---|---|---|---|---|---|---|
ANT | RT | Alerting | 0.52 |
−0.02 | 0.73 |
0.80 |
0.73 |
Orienting | 0.61 |
0.57 | 0.70 |
0.65 |
0.87 |
||
Executive | 0.77 |
0.86 |
0.57 | 0.93 |
0.92 |
||
Error | Alerting | N/A | 0.20 | 0.35 | −0.02 | −0.07 | |
Orienting | N/A | 0.42 | 0.23 | 0.32 | 0.79 |
||
Executive | N/A | 0.45 | −0.07 | 0.93 |
0.69 |
||
ANT-I | RT | Alerting | N/A | 0.64 |
−0.11 | 0.98 |
0.76 |
Orienting | N/A | 0.77 |
0.17 | 0.81 |
0.76 |
||
Executive | N/A | 0.48 | 0.79 |
0.89 |
0.96 |
||
Error | Alerting | N/A | 0.28 | −0.24 | 0.70 |
0.29 | |
Orienting | N/A | 0.43 | −0.11 | 0.02 | 0.40 | ||
Executive | N/A | 0.63 | 0.73 |
0.92 |
0.69 |
Results of the modified split-half reliability analyses as a function of number of consecutive sessions included in the analysis can be seen in Figure
For each participant, trials with improper responses (e.g., responses made before the target was presented) or trials with no responses were excluded (1.8%). Then, mean correct RT after eliminating extreme values (less than 200 ms and more than 1700 ms: less than 0.1% of the total analyzable data) and mean error rate were computed and subjected to analyses. Table
Tone |
No tone |
|||||
---|---|---|---|---|---|---|
Valid | Invalid | No cue | Valid | Invalid | No cue | |
Congruent | 615 (0.001) | 701 (0.004) | 682 (0.004) | 638 (0.002) | 706 (0.001) | 729 (0.002) |
Incongruent | 689 (0.008) | 785 (0.011) | 764 (0.007) | 711 (0.006) | 793 (0.011) | 805 (0.008) |
The mean correct RT and the mean error rate were submitted to ANOVAs with auditory signal (tone and no tone), cue condition (valid, invalid, and no cue), target congruency (congruent and incongruent) as repeated-measures factors and Session (1–10) for the Sessions 1–10 analyses.
For error rate, the interaction between cue condition and target congruency was marginally significant,
For error rate, the main effect of session was significant,
Figure
The correlation between Sessions 1 and 2 was significant only for the executive network with RT and error rate (Table
Results of the modified split-half reliability analyses as a function of number of consecutive sessions included in the analysis can be seen in Figure
In this section we will compare the magnitudes of the network scores measured by the two tests and we will explore the correlation between corresponding scores (Table
Network | ANT | ANT-I | |||
---|---|---|---|---|---|
RT | Alerting | 54.85 | 23.93 |
6.22 |
0.38 |
Orienting | 71.75 | 82.86 | −1.16 | −0.10 | |
Executive | 94.24 | 79.60 | 5.53 |
0.96 |
|
Error | Alerting | −0.00 | −0.00 |
−0.75 | 0.38 |
Orienting | −0.00 | 0.00 | −1.77 | 0.10 | |
Executive | 0.01 | 0.01 | 1.12 | 0.90 |
The present experiment was conducted to examine, in older adults, the stability, isolability, robustness, and reliability of the measures of attention network (alerting, orienting, and executive) derived from two versions of the ANT over repeated testing and difference between the two versions of the ANTs.
We observed practice effects for the executive network scores with both the ANT and the ANT-I and practice effects for the alertness scores in the ANT (Figures
The practice effects for the executive network in RT in the ANT and ANT-I are clearly apparent. A close examination of Figures
Practice effects for alerting were also observed in the ANT; the alertness network score increased as the sessions progressed. The alerting network in the ANT is defined by the double cue and no cue conditions. A close examination of Figure
Our data largely replicate previous studies of the attention networks (Fan et al.,
The network scores generated by the two tests were found to be significantly related to each other only in the executive network. This significant relation was expected because the executive effects are measured by the two tests using essentially the same conflicting and congruent arrows. Although the network scores for the alerting network were not significantly correlated, the correlation was moderate (
Examining effects of aging was not our objective in the current study. Nevertheless, such a comparison between older and young adults is made possible because we tested young adults in a previous study (Ishigami and Klein,
As noted in the results, the sample size in the current study is relatively small and makes it necessary to be cautious in interpreting the correlational analyses. However, it should be also noted that results from only Session 1 (i.e., less power) were similar to those when all 10 sessions were included (i.e., more power).
Health status was based on self-report rather than on objective measures. While the latter might be more reliable, self-report is quite typical in studies like this. Moreover, the older adults in the current study appeared to be mentally and physically healthy to the experimenter (Ishigami): being able to come to the lab by themselves and sit in front of the computer for an hour, not needing to rest excessively during the experiments, having no problems in hearing and understanding the experimenter, and remembering to come to the lab on scheduled days without being reminded in advance.
With older adults, both ANTs are useful tools to measure attention components, namely alerting, orienting, and executive functions, within one session, which takes less than 30 min. The current study shows that scores of these attention components remain robust even after 10 sessions. This enables either ANT to be used in applications that require repeated testing. It is important to note, however, that executive control scores with both ANTs decrease, and alerting with the ANT increases with practice. Therefore, an untreated control group would be warranted in some designs. While the network scores are robust against practice, their reliability is generally lower than is ideal for many purposes.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
This research was made possible by a Natural Sciences and Engineering Research Council Discovery grant to Raymond M. Klein and scholarship support to Yoko Ishigami from the Killam Trust and Multiple Sclerosis Society of Canada. The research reported here is drawn from a thesis by Yoko Ishigami in partial fulfillment of requirements for a PhD degree at the Dalhousie University.
1“Robust” means that network scores remain significantly different from zero with repeated testing.
2Although these studies report statistical non-significance between the young and the older adults, the older adults in these studies (except Tales et al., 2002 when the task was identification) show numerically greater orienting effects.
3A comprehensive picture of the patterns of endogenous orienting is difficult to draw; task (identification and detection), type of endogenous cue (central arrow and informative peripheral stimulus), and SOA (50–3000 ms) vary across the studies. It appears, however, that studies showing age differences in orienting effects typically use longer SOAs.
4When these data were analyzed using a
5Even though errors are not normally distributed, we report the results with untransformed data because the literature on inter-network correlations has more often than not analyzed them untransformed. However, we did transform the errors (arcsine-transformation) and repeat the correlational analyses with the ANT and the ANT-I. Patterns are similar except for two correlations; correlation between the alerting and the orienting networks,
6We thank Michael A. Lawrence for proving us with R scripts for the modified split-half correlational analysis.
7The same analysis was conducted for each network for each session in a separate analysis. Reliability fluctuated across session. The alerting and the orienting network scores were not reliable for any of the sessions both in RT and error rate. The executive network scores were reliable only for Sessions 2, 3, 8, 9, and 10 in RT.
8The alerting network scores in the correlational analyses were calculated including all trials. As with the ANOVA analyses above, to provide a purer measure of alerting, analyses were also carried out excluding the valid and invalid cue conditions. Significance of the correlations involving the networks was the same as those including all trials.
9The same analysis was conducted for each network for each session in a separate analysis. Reliability fluctuated across the sessions. The alerting network scores were reliable only for Session 10 in RT. The orienting network scores were reliable for Sessions 1, 2, 3, 4, and 8 with RT and for Session 7 in error rate. In RT, the executive network scores were reliable for all the sessions except Sessions 5 and 10.