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Judgment and Decision Making, Vol. 6, No. 7, October 2011, pp. 616–628
The size and distribution of donations: Effects of number of
recipients
Emre Soyer∗Robin M. Hogarth∗ †
Abstract
Whereas much literature exists on “choice overload”, less is known about effects of numbers of alternatives in do-
nation decisions. We hypothesize that donations increase with the number of recipients, albeit at a decreasing rate, and
reflect donors’ knowledge of the recipients. Donations involve different concepts of fairness—equity and equality—and
these can interact with numbers of alternatives. In two experiments, respondents indicated how they would donate lottery
winnings of 50 Euros. Results showed, first, that more was donated to non-governmental organizations and campaigns
that respondents knew better. Second, total donations increased with the number of recipients albeit at a decreasing
rate. Third, when limited to giving to only one of multiple alternatives, donors gave less than when this restriction did
not apply. Fourth, variability of donations can both increase and decrease with the number of potential recipients. We
comment on theoretical and practical implications as well as suggesting issues for future research.
Keywords: choice overload, donation decisions, fairness, equality, equity.
1 Introduction
Recently, much literature has highlighted the importance
of numbers of alternatives in choice. This can be consid-
ered from two perspectives. In one, investigators have re-
ported effects when people make unique selections from
different numbers of alternatives (e.g., Iyengar & Lep-
per, 2000; Schwartz, 2004; Scheibehenne, Greifeneder
& Todd, 2010). For example, studies have documented
differential satisfaction with choice for decisions involv-
ing pens (Shah & Wolford, 2007), pension plans (Iyen-
gar, Huberman & Jiang, 2004), gift boxes (Reutskaja &
Hogarth, 2009), and wines (Bertini, Wathieu & Iyengar,
2010). Moreover, a recent meta-analysis suggests that the
magnitude of effects depends on preconditions, choice
moderators and the contexts in which decisions are made
(Scheibehenne, Greifeneder & Todd, 2010).
The focus in the second perspective is on what happens
when people allocate resources across different numbers
of alternatives (e.g., Andreoni, 2007). This is the topic
of the present paper. Specifically, we consider this is-
sue in the context of charitable donations and investigate
the effects of numbers of alternatives on the amount of
The authors are much indebted to Germán Loewe and his col-
leagues at Netquest for facilitating the data collection. In addition, they
are grateful for comments from Paul Slovic, and the Editor and refer-
ees as well as seminar attendants at the Universitat Pompeu Fabra, the
Max Planck Institute, Jena, Germany, and TEMA, Turkey. The research
has been supported by the Spanish Ministerio de Ciencia e Innovación,
grant numbers SEJ2006–14098 and EC02009–09834.
∗Universitat Pompeu Fabra, Department of Economics and Busi-
ness, Barcelona
†ICREA, Barcelona
total donations as well as their distribution across chari-
table organizations (NGOs, non-governmental organiza-
tions) and specific campaigns. Both of these issues are
important from theoretical and practical viewpoints. For
example, when attempting to maximize donations, NGOs
might consider whether donors perceive them as belong-
ing to small or large subsets of potential recipients. At
the same time, NGOs often seek funds for different cam-
paigns and it is important to know how the number and
presentation of campaigns affect total donations.
We report two experiments. In the first, we explore
effects when donors allocate funds across different num-
bers of NGOs. In the second, we investigate what hap-
pens when a single NGO solicits contributions for differ-
ent numbers of campaigns. In short, we find two effects
of increasing the number of alternatives: total contribu-
tions increase albeit at a decreasing rate; and distributions
of donations are affected. Specifically, these tend to be-
come less egalitarian in the case of NGOs but more so
in the case of campaigns. In the second experiment, we
also investigate the use of “drop down” menus in dona-
tion interfaces for soliciting donations to specific cam-
paigns. When, as in current practice, choice is limited to
one of several alternatives, contributions are lower than
when this restriction does not apply. We conclude by dis-
cussing implications.
1.1 Relevant literature
Several recent studies have focused on different aspects
of the donation process including determinants of dona-
616
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
617
tion decisions (Landry et al., 2006; Chang, 2005), the im-
pact of presentation mode (Small, Loewenstein & Slovic,
2007), the effect of social interactions (Schweitzer &
Mach, 2008), herding behavior among donors (Martin &
Randal, 2008) and methodologies for measuring altruistic
behavior (Bekkers, 2007).
Andreoni (2007) specifically examined the effects of
numbers of recipients on donations in the context of an
experimental economics game. He found that, as the
number of recipients increased, participants gave more
but that individual shares decreased. Specifically, for “the
average subject, a gift that results in one person receiving
xis equivalent to one in which npeople receive x/n0.68
each” (Andreoni, 2007, p. 1731).
A number of studies have shown that these kinds of
results are sensitive to emotionally charged stimuli. For
example, Hsee and Rottenstreich (2004) compared the ef-
fects of affect-rich as opposed to affect-poor stimuli to
capture willingness to donate to saving from one to four
endangered pandas. With affect-poor stimuli (dots), will-
ingness to donate was greater for four endangered pandas
than one. With affect-rich stimuli (cute pictures), how-
ever, there was no difference. (But Gong & Baron, 2011,
failed to find such an interaction with similar cases.)
Related phenomena have been reported by Kogut and
Ritov (2005a; 2005b). They have identified conditions
under which people give more to help single individu-
als in need than to groups of individuals with the same
needs (see also, Dickert, Kleber, Peters, & Slovic, 2011).
The key is providing specific information about the single
individual (e.g., name and a picture) and eliciting judg-
ments in separate as opposed to joint evaluation mode
(Hsee et al., 1999).
The phenomenon that emotional responses are greater
toward individual victims as opposed to aggregates has
been termed the “collapse of compassion” and raises the
issue of why and how it occurs. Cameron and Payne
(2011) note that most studies demonstrating this phe-
nomenon have been conducted within the context of do-
nation decisions, and they argue that the collapse is not
because people lack feelings about larger numbers. In-
stead, large numbers cue people to regulate their emo-
tions, particularly when they are motivated to do so (e.g.,
when money is at stake). Cameron and Payne (2011) go
on to provide experimental evidence consistent with their
hypothesis.
Two recent studies analyzed the effects of numbers
of options on altruistic behavior without manipulating
emotions. Scheibehenne, Greifeneder and Todd (2009)
conducted an experiment involving charitable institu-
tions while studying possible moderators of choice over-
load. Specifically, participants (mainly students) were en-
dowed with 1 Euro and had to decide either to donate it
all to one institution they could choose from a specified
list or to keep the money for themselves. Their findings
suggest that more choices (represented by longer lists)
increase the proportion of donors. In addition, people
are more likely to give to charities that are better known.
Note, however, that this study did not address the issue of
allocating donations across alternative charities or multi-
ple campaigns offered by one institution. Carroll, White
and Pahl (2011) studied effects on people’s choices of the
number of alternative opportunities for volunteer work.
They found adverse effects of more choice in that deci-
sions to defer commitment were greater when there were
more alternatives.
As in the above two studies, we do not make use of
emotional stimuli in our work but (with one exception)
we do not limit choices to one of several alternatives.
1.2 Hypotheses
In conceptualizing how donors’ decisions are affected by
numbers of potential recipients, we consider three issues.
First are effects due to knowledge about the recipients.1
Second, we consider the impact of numbers of potential
recipients. And third, we speculate on how the number of
alternatives changes the distributions of donations across
recipients.
We hypothesize that donations made to specific NGOs
or campaigns increase with knowledge about them (see
also Scheibehenne, Greifeneder & Todd, 2009). This
leads to:
H1. Recipients that are better known receive more do-
nations.
When considering the impact of numbers of potential
recipients, three points are important. First, donations are
limited in that donors face budget constraints. Second,
we assume that the utility donors obtain from giving in-
creases with the size of donations but at a decreasing rate
(Andreoni, 2007). Third, we hypothesize that decisions
to make donations are sensitive to perceived needs of re-
cipients. Thus, factors that signal perceived need are im-
portant. One such factor is the number of potential recip-
ients. Our rationale is simple. If a single NGO is seeking
funds for a specific cause, that cause might be seen as im-
portant and worthy of support. However, if several NGOs
are seeking funds for the same (or similar) cause, the need
will be perceived as greater. For campaigns, similar rea-
soning applies; the larger the number of campaigns of-
fered by an NGO, the larger the perceived need.2These
points can be summarized by our second hypothesis:
1By knowledge we mean how much a person is aware of the exis-
tence of the recipient, be it an NGO or campaign.
2Saying that perceived need is a function of numbers of NGOs or
campaigns begs the interesting question of how potential donors per-
ceive specific sets of NGOs (or campaigns). This issue, however, is
beyond the scope of the present research.
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
618
H2. Donations increase with the number of potential
recipients, but at a decreasing rate.
To explore the relation between number of recipients,
perceived need, and donations, we conducted a prelim-
inary study with undergraduate students at Universitat
Pompeu Fabra. (Our main experiments involve partici-
pants from the general public in Spain.) In a survey, 40
participants were asked to imagine that they could dis-
tribute the resources of 100 NGOs to deal with four dis-
asters. These disasters had different levels of devasta-
tion and each NGO could only deal with one disaster.
For each of the four cases, the level of devastation was
provided through information on casualties, homeless-
ness and economic damages such that participants had
a clear sense of the need for help. The participants as-
signed a higher number of NGOs to cases where the need
was higher, consistent with the notion that perceived need
is positively related to the number of NGOs. In a sec-
ond survey, 35 participants hypothetically distributed 100
Euros across the same four disasters. The amounts do-
nated to disasters increased with level of devastation (i.e.,
need), but at a decreasing rate.
Finally, how are donations distributed across potential
recipients? We assume that donors seek to be fair, but
in doing so they implicitly deal with two different con-
cepts of fairness. In one, allocations reflect the relative
merits of recipients. This is known as the “equity” rule.
Second, although equity is sometimes assumed to guide
judgments of fairness, people are also sensitive to con-
siderations of “equality”. That is, a rule whereby all re-
cipients receive equal allocations (Sarbagh, Dar & Resh,
1994; Hertwig, Davis & Sulloway, 2002).
Indeed, Baron and Szymanska (2010) argue that if peo-
ple know that one NGO makes more efficient use of its re-
sources than all the others, then donors would be justified
in allocating all their donations to that NGO. However,
people are reluctant to do this and there is a diversifica-
tion bias whereby donations are distributed more equally.
How do donors reconcile the competing claims of eq-
uity and equality as the number of alternatives increases?
We suggest that two factors are important. One is that
allocations reflect perceptions of differential merit. The
second concerns the relative appeal of the equality prin-
ciple as the number of alternatives increases and for this
we envisage two possibilities: either the equality princi-
ple becomes less important as the number of alternatives
increase; or, on the contrary, it becomes more important.
A priori it is not clear which is correct. It may be that the
equality principle is difficult to ignore when there are few
alternatives. At the same time, the equality principle may
be easier to implement when there are many alternatives.
As a consequence, we state competing hypotheses:
H3a. The distribution of donations becomes less egal-
itarian across potential recipients as their numbers in-
crease (i.e., the variability of donations increases).
H3b. The distribution of donations becomes more
egalitarian across potential recipients as their numbers in-
crease (i.e., the variability of donations decreases).
We have no objective measures of donors’ judgments
of merit. Thus in our experimental work we use knowl-
edge of the NGOs and campaigns as a proxy assuming,
in effect, that donors assess merit using the recognition
heuristic (Goldstein & Gigerenzer, 2002).
Our two experiments aim to test the three hypothe-
ses. The first involves conditions with varying numbers
of NGOs; the second considers different numbers of cam-
paigns offered by a single NGO.
2 Experiment 1: Number of NGOs
2.1 Participants, design, and procedure
Participants were members of the general public in Spain
enrolled in an online market research panel. Fifty-four
percent of the 145 respondents were female and the mean
age was 35 (median 34, minimum 15, and maximum 69).
Most participants had at least a university degree.
At the beginning of a 40-minute market Web survey
on an unrelated topic, they were informed that, in addi-
tion to the fixed remuneration for their participation, they
had been entered in a lottery and had the chance of win-
ning 50C (expressed as 500 points) at the end of the ses-
sion. Once the survey ended, they were notified that, if
they wished, they could donate as much as they wanted
of their lottery winnings (from 0 to 500 points) to cer-
tain specified NGOs, split between recipients in any way
they desired. The online setup guaranteed anonymity of
responses. After making their choices, one person was
to be chosen at random and given the extra 50C, less the
amount of her/his donations. Thus, if the winner of the
lottery donated 0, s/he would get to keep 50C; if s/he do-
nated, say, 30C, s/he would get to keep 20 C. The money
donated would go to precisely those NGOs specified by
the winner.
The names of the NGOs were provided along with the
information that their common agenda is to aid under-
privileged children. The respondents were allocated at
random to three groups where they faced an alphabetical
list of:
• 3 NGOs (condition NGO_3 with 54 respondents)
• 8 NGOs (condition NGO_8 with 43 respondents)
• 16 NGOs (condition NGO_16 with 48 respondents)
The specific NGOs were selected after searching in the
internet and popular media for international organizations
with a charity agenda involving underprivileged children.
The names of NGOs presented in these three conditions
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
619
are shown in Table 1, in the order in which they were
listed.
After making their decisions, respondents rated all 16
NGOs by indicating how much they knew about each
prior to the experiment as follows: “0” implied that they
had not heard of it, “1” that they had heard of it, “2”
that they knew it, and “3” that the NGO is “very fa-
mous”. Only six respondents claimed to have heard of
all 16 NGOs and four of the 16 NGOs received average
ratings greater than 1 on what we call the “knowledge
score”. These data suggest that 16 NGOs represented a
large choice set.
2.2 Results
Table 2 lists the different NGOs in the order of their mean
popularity scores that are indicated on the right hand side
of the table. Here we also report the proportions of partic-
ipants who stated that they had never heard of the respec-
tive NGOs. Four NGOs are quite well known whereas
the other twelve are largely unknown. These results make
sense within the Spanish context of the study. Unicef, for
example, has a sponsorship deal with the Barcelona Foot-
ball Cub that is very popular in the region where the study
took place. Mercy Corps, on the other hand, is not well
known within Spain.
The intermediate columns of Table 2 show the mean
donations in points in the three experimental conditions.
Results in Table 2 support hypothesis H1 at an aggre-
gate level. Mean knowledge scores of the NGOs corre-
late (in an ordinal sense) with mean donations (the bet-
ter known NGOs receiving larger contributions). Spear-
man’s rho is 1.00 for NGO_3; 0.64 (p= .10) for NGO_8;
and 0.47 (p= .07) for NGO_16.
To estimate the effect of knowledge at the level of in-
dividual donations, we regressed individual donation de-
cisions (n= 1274) on knowledge scores. Controlling for
individual NGO effects, number of alternatives and ad-
justing the standard errors for clusters of 145 different
donors, we obtain a statistically significant coefficient of
17.1 (s.e. = 2.9, p= .001) for the knowledge score. The
F-ratio of the analysis is F(16, 144) = 18.6, with p= .001,
R2=.25 and root-MSE = 71.7. These results indicate that
both at the aggregate and individual levels, better known
recipients obtain larger contributions.
Our second hypothesis (H2) is that, overall, donations
increase with the number of recipients but at decreasing
rate. Figure 1 shows mean donations as a function of ex-
perimental conditions. An analysis of variance indicates
that the effect of number of alternatives on donations is
significant (F(2, 142) = 2.98, p= .05). When we look
at pairwise contrasts and effect sizes between the mean
donations, we find that the mean in condition NGO_8 is
Figure 1: Mean donations in the three conditions in Ex-
periment 1.
0 100 200 300 400 500
Number of NGOs
Donations (points)
236
314 326
3 8 16
greater than in condition NGO_3 (314 vs. 236, z= 1.91,
p= .06, Cohen’s d= .52); and the mean in condition
NGO_16 at 326 is also greater than in condition NGO_3
(z= 2.23, p= .03, Cohen’s d= .54). Finally, the difference
between the means for condition NGO_16 and NGO_8 is
not statistically significant with a medium effect size (326
vs. 314, z= 0.3, p= .78, Cohen’s d= .42). Post-hoc mul-
tiple comparisons through Tukey’s HSD test find only a
difference between the means for NGO_16 and NGO_3
(q= 3.08, p= .08).
Further evidence that donations increase with the num-
ber of potential recipients can be seen in Table 3 where
we provide data characterizing individual contributions.
As the number of potential recipients rises, so does
the proportion of participants who donate their total en-
dowment of 500 points—from 24% (NGO_3) to 37%
(NGO_8) to 50% (NGO_16). (The difference between
NGO_16 and NGO_3 is significant, z= 2.8, p= .01).
Moreover, note that whereas 30% of participants donate
nothing when there are only three NGOs, this figure drops
to 19% for the cases with 8 and 16 alternatives.
Hypotheses H3a and H3b make contrary predictions—
increasing as opposed to decreasing variability in dona-
tions as the number of alternatives increases. At the ag-
gregate level, the variances of the contributions to the
different NGOs are 582, 1556 and 1549 in conditions
NGO_3, NGO_8, and NGO_16, respectively. The F-
tests for the difference in variances between NGO_3 and
NGO_16 (F(15, 2) = 2.67, p= .30) and between NGO_3
and NGO_8 (F(7, 2) = 2.67, p= .30) indicate that the
change in the variability of donations is not significant.
Moreover, an analysis of variance on variances of dona-
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
620
Table 1: NGO options across conditions in Experiment 1.
NGO_3 NGO_8 NGO_16
Mercy Corps Children’s Network International Care
Oxfam Every Child Children in Crisis
Unicef Global Fund for Children Children’s Network International
Mercy Corps EveryChild
Oxfam Global Fund for Children
Stop Child Poverty Médecins Sans Frontières
Unicef Mercy Corps
United Children’s Fund Oxfam
Plan International
Serving Our World
Save the Children
SOS Kinderdorf International
Stop Child Poverty
Unicef
United Children’s Fund
World Emergency Relief
tions by individuals shows that the effect of number of
available NGOs on the variance of donations is again not
significant (F(2, 142) = 1.54, p= .22).
On the other hand, in terms of the distribution of do-
nations, in condition NGO_3, all potential recipients re-
ceive substantial donations. In condition NGO_8, four
(or 50%) receive 76% of the contributions, and in condi-
tion NGO_16, four (or 25%) receive 92% of the contri-
butions. These overall trends are also supported by the
data summarized in Table 3; whereas 24% of participants
adopt the strategy of giving the same non-zero amounts
to all participants when there are three NGOs, this figure
is zero for the case with 16 NGOs. These latter results
are consistent with the hypothesis that the variability of
donations is positively related to the number of NGOs.
Finally, it is of interest to note how changes in the num-
ber of alternatives affect the fortunes of different NGOs.
When there are only three NGOs, Mercy Corps receives
a large average donation despite being unknown. How-
ever, this changes dramatically as the number of alter-
natives increases. Unicef, on the other hand, retains its
leading position, its relative share and its donation in ab-
solute terms as the number of alternatives increases. Ox-
fam sees reductions in donations as the number of alter-
natives increases. However, being known appears to save
Oxfam from the extreme reductions from which Mercy
Corps suffers as the number of alternatives increases.
3 Experiment 2: Number of cam-
paigns
Experiment 2 was designed to replicate the results of Ex-
periment 1. However, it involved varying numbers of
campaigns instead of varying numbers of NGOs.
3.1 Participants, design, and procedure
The design and procedure of this second study were anal-
ogous to Experiment 1. The respondents, who were en-
tered in a 50C lottery (expressed as 500 points) after par-
ticipating in an unrelated survey, were notified that they
could make a donation (of between 0 and 500 points) if
they wished at the end of the session. The participants
were again members of the general public in Spain en-
rolled in a market research panel. Fifty percent of the
505 respondents were female and the mean age was 38
(median 38, minimum 18, and maximum 74). Most par-
ticipants had at least a university degree.
Unlike participants in Experiment 1, who had to decide
among charitable institutions, participants in this study
faced different numbers of campaigns offered by a sin-
gle, well known NGO: Unicef. The study had a between-
subject design involving five conditions to which respon-
dents were allocated at random. Three conditions in-
volved different numbers of campaigns (1, 7, and 13)
and the two further conditions varied the number of op-
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
621
Table 2: Donation decisions by knowledge and number of alternatives in Experiment 1.
NGOs Mean donations in points (stdev) Mean knowledge
score
Knowledge
score = 0 (%)
Condition NGO_3 NGO_8 NGO_16
N 54 43 48
No. of NGOs 3 8 16
Unicef 100 (97) 128 (163) 142 (181) 2.59 3
Médicins Sans Frontières x x 79 (157) 2.30 8
Oxfam 83 (80) 67 (118) 52 (102) 2.01 14
Save the Children x x 29 (53) 1.32 34
Global Fund for Children x 26 (46) 0 (2) 0.44 75
Mercy Corps 53 (65) 16 (25) 0 (2) 0.39 78
Plan International x x 0 (2) 0.39 77
United Children’s Fund x 18 (28) 2 (14) 0.37 76
SOS Kinderdorf International x x 9 (39) 0.24 84
Children’s Network International x 17 (27) 1 (7) 0.21 84
Serving Our World x x 3 (15) 0.21 86
Stop Child Poverty x 25 (51) 3 (15) 0.20 87
EveryChild x 18 (28) 1 (7) 0.19 88
Care x x 0 (2) 0.17 86
World Emergency Relief x x 3 (15) 0.17 88
Children in Crisis x x 1 (7) 0.16 87
Total 236 314 326
tions that could be chosen when there were 7 and 13
campaigns. Specifically, in the former respondents could
donate to only one of several options (from 7 or 13),
whereas in the latter they could distribute their contribu-
tions across several options (out of 7 or 13).
In summary, there were five groups, each with 101 re-
spondents, facing lists of:
• 1 campaign (condition Only_1)
• 7 campaigns (condition Single_7; campaigns were
listed in a drop down menu, where donations could
only be made to a single option)
• 13 campaigns (condition Single_13; campaigns
were listed in a drop down menu, where donations
could only be made to a single option)
• 7 campaigns (condition Multiple_7; campaigns
were listed in an open menu where donations could
be distributed across multiple options)
• 13 campaigns (condition Multiple_13; campaigns
were listed in an open menu where donations could
be distributed across multiple options)
The difference between conditions Single_7 and Mul-
tiple_7, and conditions Single_13 and Multiple_13, lies
in how the options are displayed. In all the online sites of
Unicef and the majority of NGOs featuring multiple cam-
paigns, the alternatives are exclusively listed in a drop
down menu (analogous to conditions Single_7 and Sin-
gle_13). Hence contributors are constrained to make a
selection from a list and to donate to a single recipient,
that is, without being able to distribute their donations
across alternatives (unless they revisit the site). We in-
cluded Multiple_7 and Multiple_13 in order to observe
whether the elimination of this constraint would encour-
age donors to distribute their contributions over multiple
campaigns and thus change the distribution and, more im-
portantly, the amount of contributions. As will be shown
below, this change does have an impact.
The specific campaigns were selected following a sur-
vey of Unicef’s campaigns in its 36 national websites
in April 2011 (campaign compositions change depend-
ing on the occurrence of disasters). The campaigns pre-
sented in these five conditions are shown in Table 4. In
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
622
Table 3: Proportions of donation behavior in Experiment 1.
NGO_3 NGO_8 NGO_16
% of participants giving equal non-zero amounts 24 23 0
% of participants giving away 0 points 30 19 19
% of participants giving away all 500 points 24 37 50
Table 4: Unicef campaigns across conditions in Experiment 2.
Only_1 Single_7 & Multiple_7 Single_13 & Multiple_13
Unicef (where most needed) Where most needed Where most needed
Haiti, after one year Haiti, after one year
Emergency fund Emergency fund
Floods in Pakistan Floods in Pakistan
Libyan crisis Libyan crisis
Earthquake and tsunami in Japan Earthquake and tsunami in Japan
Water for Niger Water for Niger
United against hunger
Fight against malaria
Clean drinking water
Children’s education
Humanitarian aid for Sudan
Promotion of Unicef
condition Only_1, participants were asked if they would
consider donating to Unicef (without mentioning a spe-
cific campaign), who then would decide how to use the
contributions. In all the other conditions, the option
“where most needed” was featured at the top of the op-
tions list, whereas the remainder of campaigns were dis-
played in an order randomized for each participant. (This
structure mimics donation sites that feature multiple op-
tions.) The campaigns in conditions Single_7 and Mul-
tiple_7 were the ones available in Unicef’s Spanish site
(www.unicef.es) in April 2011, whereas the six addi-
tional campaigns featured in Single_13 and Multiple_13
are among those that are frequently featured in Unicef’s
other national sites.
The number of alternatives featured in different condi-
tions is consistent with the current available numbers of
options offered by Unicef and many other NGOs. Specif-
ically, as of April 2011, across all websites where one can
make a one-time donation to Unicef, the mean number of
campaigns from which to choose is 7 (SD = 12.8). When
the German site is excluded (this site offers an unusu-
ally large number of 72 alternative campaigns), this figure
drops to 5 (SD = 4.5). One third of these sites offer only
one alternative (denoted as “where most needed”), and
only 15% feature more than 10. Hence, while condition
Only_1 mimics the majority of situations encountered in
online environments, conditions Single_7 and Multiple_7
represent average situations across all sites. Given current
practice, conditions with 13 choices (e.g. conditions Sin-
gle_13 and Multiple_13) constitute a valid analogy for
large sets of alternatives.
As in Experiment 1, after making their donation de-
cisions, respondents rated all 12 campaigns (excluding
“where most needed”) by indicating how much they knew
about each prior to the experiment as follows: “0” im-
plied that they had not heard of it, “1” that they had heard
of it, “2” that they knew it, and “3” that the campaign is
“very well known”.
3.2 Results
In Table 5, the different Unicef campaigns are listed in
the order of their mean knowledge scores that are indi-
cated in the column on the right hand side of the table.
Here, we again report the proportions of participants who
stated that they had never heard of the respective cam-
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
623
Table 5: Donation decisions by knowledge and number of alternatives in Experiment 2.
Unicef campaigns Mean donations in points (stdev)
Mean
knowledge
score
Knowledge
score = 0
(%)
Condition Only_1 Single_7 Single_13 Multiple_7 Multiple_13
N101 101 101 101 101
No. of campaigns 1 7 13 7 13
Where most needed 149 (148) 102 (149) 74 (142) 120 (158) 93 (146) 2.59∗3
Japan earthquake/tsunami x 19 (64) 13 (56) 28 (67) 18 (52) 1.55 13
Haiti, after one year x 35 (103) 5 (39) 27 (65) 16 (45) 1.24 20
United against hunger x x 20 (85) x 23 (53) 1.15 23
Fight against malaria x x 0 (0) x 11 (25) 1.11 23
Children’s education x x 22 (73) x 20 (53) 0.99 33
Libyan crisis x 5 (50) 0 (0) 10 (23) 4 (13) 0.93 41
Clean drinking water x x 19 (77) x 18 (38) 0.84 42
Promotion of Unicef x x 19 (85) x 27 (94) 0.70 53
Emergency fund x 16 (55) 1 (10) 20 (61) 9 (23) 0.67 52
Sudan humanitarian aid x x 0 (0) x 6 (17) 0.59 55
Floods in Pakistan x 0 (0) 0 (0) 11 (24) 5 (12) 0.53 60
Water for Niger x 12 (62) 5 (33) 11 (23) 5 (17) 0.28 79
Total 149 188 179 227 255
∗The knowledge score for the option “where most needed” was taken from Experiment 1, knowledge score of
Unicef.
paigns. The campaign “where most needed” has been as-
signed the knowledge score of Unicef from Experiment
1. Among other campaigns, our participants were rela-
tively more knowledgeable about two recent (as of April
2011) and highly publicized specific disasters (Japan and
Haiti) and two general causes (eradication of hunger and
malaria).
The intermediate columns of Table 5 show the mean
donations in points for the five experimental conditions.
Results support H1 at an aggregate level. As in Ex-
periment 1, the mean knowledge scores of the campaigns
correlate (in an ordinal sense) with mean donations (the
better known campaigns receiving larger overall contri-
butions). Spearman’s rho is .79 (p= .05) for both Sin-
gle_7 and Multiple_7; .49 (p= .08) for Single_13; and
.63 (p= .03) for Multiple_13.
To identify the effect of knowledge at an individual
level, we regressed individual donation decisions (ex-
cluding the ones made for “where most needed”, which
lacks the individual knowledge score) on knowledge
scores (n= 3636). Controlling for campaign effects,
number of alternatives and presence of a drop down
menu, and adjusting the standard errors for clusters of
404 different donors, we obtain a statistically significant
coefficient of 7.1 (s.e. = 1.15, p= .001) for the knowledge
score. The F-ratio of the analysis is F(14, 403) = 12.0,
with p= .001, R2=.04 and root-MSE = 50.3. These re-
sults suggest that both at the aggregate and individual lev-
els, better known campaigns obtain larger contributions.
The results are in line with H2. Figure 2 shows mean
donations as a function of experimental conditions. Vi-
sually, this suggests a main effect for the Multiple as op-
posed to the Single conditions (the means for the former
being larger than those of the latter). A two-way factorial
analysis of variance shows that both number of alterna-
tives and drop down menus have significant impacts on
donations (F(4, 500) = 6.52, p= .001). The effect of num-
ber of alternatives yields an F-ratio of F(2, 500) = 10.78
with p= .001, and the ratio for the effect of drop down
menu is F(1, 500) = 12.01 with p= .001. The interaction
effect is not significant. Post-hoc multiple comparisons
using Tukey’s HSD test reveal that the donations to Mul-
tiple_7 and Multiple_13 are higher than Only_1 (q= 4.8
with p= .001 and q= 6.5 with p= .001, respectively).
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
624
Table 6: Proportions of donation behavior in Experiment 2.
Only_1 Single_7 Single_13 Multiple_7 Multiple_13
% of participants giving equal non-zero amounts x x x 6 4
% of participants giving away 0 points 31 22 26 20 15
% of participants giving away all 500 points 8 9 10 22 18
Figure 2: Mean donations in the five conditions in Exper-
iment 2.
0 100 200 300 400 500
Number of campaigns
Donations (points)
149
227 255
149 188 179
Multiple
Single
1 7 13
In terms of specific pairwise contrasts and effect sizes,
we find that when participants were constrained to select
a single option, the mean donation in condition Single_7
is greater than in condition Only_1 (188 vs. 149, z= 1.9,
p= .06, Cohen’s d= .27). The mean for condition Sin-
gle_13 at 179 is not statistically different than those for
Only_1 and Single_7. However, when the mean for con-
dition Only_1 is compared with those for conditions Mul-
tiple_7 (227) and Multiple_13 (255), the differences are
significant with larger effect sizes (z= 3.3, p= .001, Co-
hen’s d= .47 and z= 4.7, p= .001 Cohen’s d= .67 respec-
tively). Given the structural similarity of these conditions
to NGO_3, NGO_8 and NGO_16, these last results echo
the findings of Experiment 1.
The effect of allowing donors to distribute their con-
tributions over the available options can be further ob-
served in Table 6 where we provide data characterizing
individual contributions. Similar to Experiment 1, as the
number of potential recipients rises, so does the propor-
tion of participants who donate their total endowment of
500 points—from 8% (Only_1) to 22% (Multiple_7) and
18% (Multiple_13). (The difference between Multiple_7
and Only_1 is significant, z= 2.8, p= .01 and so is the
difference between Mutiple_13 and Only_1, z= 2.2, p=
.03). Moreover, note that whereas 31% of participants
donate nothing when there is only one option, this figure
drops to 20% and 15% for the cases with 7 and 13 Mul-
tiple alternatives (the difference is significant for condi-
tions Only_1 and Multiple_13, z= 2.73, p= .01).
The data of Experiment 2 appear to reject H3a, the hy-
pothesis that the variability of donations increases with
numbers of alternatives. At the aggregate level, the vari-
ances of the contributions to the different campaigns are
1209, 403, 1548 and 538 in conditions Single_7, Sin-
gle_13, Multiple_7 and Multiple_13, respectively. The
F-tests for the difference in variances between Single_7
and Single_13 (F(6, 12) = 3.00, p= .05) and between
Multiple_7 and Multiple_13 (F(6, 12) = 2.88, p= .06)
indicate that the variability of donations decreases as the
number of alternatives increases thereby supporting H3b.
Moreover, a two-way factorial analysis of variance on
variances of individuals’ donations shows that the nega-
tive effect of number of available campaigns on the vari-
ance of donations is again significant (F(1, 400) = 15.84,
p= .001), whereas neither the effect of using a drop down
menu, nor the effect of the interaction term is significant.
In terms of the distribution of donations, each cam-
paign, including the option “where most needed”, suffers
reductions in both absolute terms and in shares within to-
tal donations as the number of alternatives increases.
4 Discussion
We conducted two experiments that investigated effects
on charitable donations when these are allocated to vary-
ing numbers of recipients. The tasks in our experiments
differed in two ways. In one, recipients were different
NGOs; in the other, recipients were different campaigns
of the same NGO. Unlike the former, the latter also in-
volved conditions that limited donors to allocating their
whole donation to one of several recipients.
We hypothesized that better known recipients would
receive more donations than lesser known recipients
(H1). We showed this to be the case in both Experiment
1 and 2 at the aggregate as well as individual levels.
To measure knowledge of NGOs and campaigns, we
explicitly adopted a simple strategy of only asking our
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
625
respondents whether they had heard of these (on a scale
from “not having heard” to “well known”). We did not
inquire about the nature of respondents’ knowledge or at-
titudes. Moreover, we used knowledge scores as a proxy
for respondents’ assessments of the merits of NGOs and
campaigns (appealing to the recognition heuristic, Gold-
stein & Gigerenzer, 2002). Clearly, however, the fact that
a respondent is knowledgeable about an NGO does not
necessarily imply a positive attitude. It would be appro-
priate to elicit knowledge in a more complete manner in
future research.
One intriguing finding was the apparent interaction
between knowledge and number of potential recipients
as the latter increases. Consider the donations made in
Experiment 1 to the three NGOs in condition NGO_3,
namely Unicef, Oxfam, and Mercy Corps. In condition
NGO_3, two well-known NGOs, Unicef and Oxfam, re-
ceive large mean donations (100 and 83), and even the
little known Mercy Corps receives 53. As the numbers
of recipients increase, Unicef—the best known NGO—
maintains its share of total donations (some 40%) and so
benefits in absolute terms as overall donations grow. On
the other hand, both Oxfam and Mercy Corps see reduc-
tions. In the case of Mercy Corps, the drop-off is dra-
matic: from 53 (NGO_3) to 16 (NGO_8) to 0 (NGO_16).
The data of both experiments support our second hy-
pothesis that donations increase with the number of po-
tential recipients, but at a decreasing rate. In Experiment
1, there is a 33% increase in mean donations as the num-
ber of recipients increases from three to eight (236 to
314), and a 38% increase from three to 16 (236 to 326).
In the Multiple condition of Experiment 2, the increase
from a single recipient to seven is 52% (149 to 227), and
71% from the single to 13 recipients (149 to 255). These
are important results from both theoretical and practical
perspectives.
One of the rationales underlying H2 is that the pres-
ence of recipients is a cue to need and that respondents
are sensitive to this. Indeed, the results of our two sur-
veys with undergraduate students suggested that there is
a relation in people’s minds between need and numbers of
NGOs. However, we neither measured nor manipulated
need independently in our experiments and thus cannot
rule out the possibility that some other explanation drives
the increases in donations that we observed. On the other
hand, our assumption that people gain more utility from
being more generous is similar to that of Andreoni (2007)
who—subject to one exception—observed behavior sim-
ilar to our results in the setting of an experimental eco-
nomics game.
Andreoni’s (2007) model predicts that, when the num-
ber of recipients increases, those recipients who are
present in the different conditions each receive smaller
donations (even though total donations increase). This
is precisely the pattern of results we observed in Exper-
iment 2. However, in Experiment 1, Unicef (the best-
known NGO) was an exception to the rule in that, as the
number of recipients increased, so did the donations it re-
ceived. It is possible that respondents view donating to
NGOs differently from donating to campaigns and this
possibility should be investigated in future research.
Although not explicitly related to H2, the finding in
Experiment 2 that donations were greater when respon-
dents could give to several recipients as opposed to being
limited to a single option is important. In particular, it
suggests that NGOs should consider revising the current
design of the drop down menus of their online sites. Of
course, one difference between our experimental set up
and the online sites of NGOs is that in the Single condi-
tions we did not allow respondents to access the list of
potential recipients more than once. It is an open empiri-
cal question as to whether the procedures used by NGOs
do in fact discourage potential donors from engaging in
repeated interactions with drop down menus.
Hypothesis 3 considers the possibility that as the num-
ber of recipients increases so does the variability in dona-
tions. We framed this question as involving the extent to
which respondents—in attempting to be fair—place more
or less weight on considerations of equality as opposed
to equity as numbers of recipients change. The results of
Experiment 1 are ambiguous in that whereas some mea-
sures support more variance as numbers of alternatives
increase, others suggest no difference. On the other hand,
in Experiment 2 variance in donations decreases as the
number of alternatives increases. Once again, we are led
to suspect that people think differently about donations to
NGOs and donations to campaigns.
Figure 3 summarizes our results by showing donation
amounts across the eight experimental conditions of our
two experiments. The innovation of the present work is
to consider how the number of potential recipients affects
donation decisions in terms of both amounts and distri-
butions across alternatives. That there are such effects is
important from both theoretical and practical viewpoints.
From a theoretical perspective our approach can be de-
scribed as cognitive in nature. It does not account for
emotional considerations that have been shown to be im-
portant in donation decisions (Dickert, Sagara & Slovic,
2011) and that can, in turn, be mediated by individual dif-
ferences such as numeracy (Dickert et al., 2011). Thus
extending our work to incorporate the effects of emo-
tional influences and individual differences is important
for future research.
At a practical level, our results emphasize the impor-
tance of the reputation of NGOs and the size of the mar-
kets in which they compete for funds. If market size is
captured by the number of potential recipients, then it
pays for leading NGOs to seek large, competitive “mar-
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
626
Figure 3: Visualization of donations made to recipients across all eight experimental conditions, as a function of
knowledge score.
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0 50 100 150 200
Mean donation (points)
Unicef
Oxfam
Mercy Corps
NGO_3
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0 50 100 150 200
Mean donation (points)
Unicef
Oxfam
NGO_8
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0 50 100 150 200
Mean donation (points)
Unicef
Oxfam
Médecins Sans Frontières
Save the Children
NGO_16
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0 50 100 150 200
Knowledge score
Mean donation (points)
Where most needed
Only_1
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0 50 100 150 200
Mean donation (points)
Where most needed
Haiti, after one year
Japan earthquake/tsunami
Single_7
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0 50 100 150 200
Mean donation (points)
Where most needed
Japan earthquake/tsunami
Single_13
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0 50 100 150 200
Mean donation (points)
Where most needed
Haiti, after one year Japan earthquake/tsunami
Multiple_7
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0 50 100 150 200
Knowledge score
Mean donation (points)
Where most needed
Japan earthquake/tsunami
Multiple_13
Judgment and Decision Making, Vol. 6, No. 7, October 2011 Number of choices and donation decisions
627
kets”. Lesser known NGOs, however, should avoid com-
petition. On the other hand, featuring multiple campaigns
is beneficial for resource generation, so long as donors are
not constrained to a single option when making a contri-
bution. Given that almost all NGOs employ such limita-
tions in their current online sites and donation interfaces,
our results have implications for improving processes of
resource generation.
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